There's been a lot of discussion about open carry vs concealed, including an excellent piece from Gruntpa.  Here's my perspective as a retired LEO.

When I got out of the Army as a forward observer with the 82nd Airplane Gang, I found out that the only thing I was qualified to do was tend bar or become a cop.  

I naturally started as a uniformed officer, then as a plain clothes narcotics guy.   Plain clothes = concealed carry.  If I was providing overwatch or surveillance, I used a good holster (Safariland SLS version). Since bad guys don't use holsters, if I was working undercover, waistband or boot was the only option.

Carrying concealed gave me the freedom of knowing that no one really knew I was carrying.  Gray man and all that.  Blend in.  No noteworthy messages on t shirts, no fancy boots or kicks, no expensive coats.  

Oh yeah.  And every male who ends up in a narcotics unit inevitably grows all manner of facial hair:  the soul patch, the Zapata mustache, the goat, the VanDyke, the full VetBro beard, the biker chest-level King Tut chin spinach, the Sonny Crockett designer Armani stubble.

In a small city, the bad guys inevitably find out who you are.  You end up farmed out to other jurisdictions, where you're not known.  Same goes for the guys from other agencies who are sent to your town.

One thing doesn't change, though. You always end up carrying.  When you're off duty, it's gotta be concealed.  The bad guys ran our plates through allies at DMV or insurance companies. They had our addresses.  More than a few times, I was followed (in the direction of) home.  Since I lived rural, it was always a hoot to lead the bad guys out to our version of Appalachia, lead them down some dirt road, then kick it in the ass, leave a cloud of dust, and leave them there out of cell or GPS range.

Also, carrying concealed gave me the peace of mind of knowing that the bad guy wasn't eyeing my holstered weapon, and trying to figure out if he could overpower me, take it, and use that round in the chamber to send me to meet my Grandfathers.

After Narco, I got promoted and went back on the road as a uniformed Sgt, running a shift.  Towards the end of my career, one of my guys, a dearly loved friend whom I went to the Academy with, had a deadly encounter.

At the time, we were using what we thought was the Cat's Ass of uniformed duty holsters.  A Level III (3 different security features to defeat before the gun comes out) holster that fit our light-equipped .40 cal Glock 22 full sized duty pistols: the Blackhawk Serpa Level III Duty Holster for a Glock 22 equipped with the Streamlight TLR-1 weapons light.  I had worked with it on the range with SWAT, as a firearms instructor at my department, and as a firearms instructor at the Academy, teaching brand-new civilians/recruits.  It was fast, it was intuitive, it was secure.

Or so I thought.

Trouble with it began to manifest. One winter night, our SWAT was called to arrest a murder suspect.  He had robbed a convenience store out of state, and after he got the money, just for shits and grins, gunned down the compliant clerk.  This turd was holed up in a house in our area.  We surrounded the house and called him outside via loudspeaker.  It was 10 degrees and snowy, and me and my wingman were laying in a snowbank lined up with the left-front corner of the house.  The guy eventually came out with his hands up.  I covered my wingman as he stood up and attempted to draw his pistol.  The holster was frozen shut.  A wad of ice had formed and was lodged behind the Serpa's release button.  He was now out of service.  Pretty sobering.

This stuff continued in training.  Dirt, mud, pieces of mulch would periodically get caught in that spot and hang the holster up.

But, back to my academy buddy.  My friend "K" was sitting in his patrol car getting ready to do some paperwork in a closed gas station parking lot.  He called his wingman over to watch his 6 before starting, due to the sheer number of ambushes of police in public.  It was part of our current training regimen and policy.  

He sat waiting until he saw a guy sneaking up on the driver's side.  The guy slapped the side of the patrol car and started yelling.  K exited to create some space, and the fight was on.

The bad guy (clearly troubled, but trying to turn his life around) grappled with K in a standing position.  As with most light-equipped weapons, there was a gap to allow for the attached light to fit in the holster. The bad guy got a finger inside the holster and got to the trigger.  The round put an entry and exit hole in K's duty pants, and creased the skin on his leg.  He shoved the guy to disengage and went to draw his duty gun.

The bad news?  The entire holster, with gun inside, was gone from the duty belt. The bad guy had managed to pluck the whole thing off K's belt. The good news? The bad guy couldn't figure out (but was trying mightily) how to get it out of the holster.  More good news?  It was a dead gun, since the weapon didn't cycle in the closed holster.  Of course, you're not thinking of this while you're looking at a crazed individual trying to kill you WITH YOUR OWN GUN.

At this exact time, K's wingman showed up, saw what was happening, and engaged.  "B" is an OIF veteran of the Big Red One who Remembered the Face of His Father.  A tattooed gunslinger and 12th Degree Ninja.  He's now SWAT, and teaches this encounter at police academies all over.

He fired 12 rounds of .40 caliber.  11 hits in the dark, at a range of @ 6 yards, under stress. The fatal hit was to the iliac artery (low center mass) on the 3rd or 4th round.  More back-up showed up.  20 minutes later, the bad guy was still fighting while being strapped to a gurney and flown to a trauma center.

Think about that.  Fatal shot to the iliac artery.  20 minutes to pump failure, where he stopped struggling. He expired in the chopper.

Months after the shooting, I was put in charge of the internal review, from a lessons-learned standpoint.  All legal considerations had been addressed and dismissed by a Grand Jury.

Part of this review was equipment performance.  We contacted Blackhawk.  They shipped us a completely new inventory of holsters, free of charge.  We took the current ones out of service and began testing them.  Many failed from the exact stresses encountered during the incident.  So we tested the new ones. They failed at a rate approaching 50%.  

These failures included the plastic breaking around mounting points, screws separating from their threaded nuts, and mounts themselves cracking.  It was especially vulnerable to a twisting maneuver of the entire holster while mounted on a duty belt.

The higher-ups at Blackhawk (Blackhawk was originally founded by a retired Navy SEAL, then sold to a Minnesota based outdoor company) personally came to our Dept with a brand new, improved version of their holster.  They gave us 20 copies.

We tested them in the same fashion.  Five out of the first six failed in some way. We ended the testing, and our use of this holster system for duty guns. (We still used them for Tasers.)

In looking for a new holster, we had needs.  It needed to be a Level III.  It needed to fit a Glock 22.  And it needed to accommodate a Streamlight TLR-1 equipped Glock 22.  And, it had to be able to convert easily to a concealed version for our detectives/plain clothes.

At the time, there were very few holsters that met this criteria.  We went with the Safariland SLS/ALS series of duty holsters with the thumb shield, rotating hood, and release lever.

Solid holster.  The kydex is thick, but pliable.  It bends, but does not break. The Blackhawk was brittle by comparison.  For the testing, I was the wearer.  Imagine 200+ pound men hanging their body weight off a holster.  Imagine them tugging at it at combat speed.  Imagine them twisting the whole holster clockwise, then counter-clockwise, like a windlass in a human-sized tourniquet.  Then you can imagine the bruises from my rib cage to my upper thighs.  

There was not one failure, including pulling the protective hood out of the way to get inside.

The only hang-up?  As previously stated, if it's got a weapons light attached, chances are you can get a finger inside, unless it's one of the newer generation micro lights like the TLR-7.

So, this brings me back to one of the original discussions, open vs. concealed carry.

As a uniformed cop, you're obviously carrying openly.  You are used to people all day long looking and taking note of your equipment.  There's a reason lots of cops stand there with their forearms on top of their holstered guns and mag pouches. It's a passive way to defeat the average Joe from figuring out your shit.  It's also why Safariland puts that weird shield closest to the belt line, over top of the rotating hood.  It's one more thing a bad guy has to defeat to get to your gun, keeps him/her from seeing the mechanism(s) needed to access the gun from the holster, but doesn't affect your draw in any way.

And this concept of passive protection leads to active.  Gun grabs are real. Most attacks come from the rear, so kidney carry and small of back carry can start bad and end worse.

Your number one mission is to prevent that bad guy from getting that gun out, so you need to lock it down in that holster while you simultaneously attack.  This can be as simple as grabbing around (not covering) the muzzle end and flipping the whole shebang inward towards the rib cage.  The better the attachment method, like belt-slide, the better it works.  Paddle attachments are a little looser and vulnerable, but still work.

Most of us carry blades.  If you're defending a gun grab, it's a deadly force encounter.  That blade can be your lifeline.  Those of us who've openly carried usually carry a knife on the support side because of this.  If your carry side hand is busy keeping that gun locked down, it can't get to the blade on that side, and your support hand can't reach it.

So, from the perspective of a guy that has openly carried a lot, and has concealed a lot, my preference happens to be concealed.  I take nothing away from those who decide to carry open.  Both have their strengths and weaknesses.  For open carry, cheap plastic, cloth, or leather are risky.  As are half-assed attachment methods. For either method, a blade is a sine qua non. (That's some Latin just for Gruntpa.)

Finally, I'm no raving expert.  I'm just offering a perspective from my personal experience.

Stay safe.