I'm running one on my 10" gun. Since 2/3 of the agencies I've taught and talked with are using or switching to shorties for dedicated entry teams, I left it on that upper. The 14.5"+ guns don't need a comp in my opinion. I haven't been able to run it in a true, closed up house yet but even in open top dedtcated shoothouses, it will blow small picture frames off the walls when running them. When you have several of them running together, you definately pay more attention to your relative position a bit better, esuring you are on line/arch or nor sticking your face too close to a muzzle. Concussion is more noticable than an A2 of course, however with guys trying out PWS & other more agressive brakes, it is MUCH better than any other brake I've seen run. Noise is about the same as normal with 4-5 guys shooting in a shoothouse and with your comms gear and plugs in. In low light, flash is intermittent; some barely noticable, some fireballs. Depends on ammo & burn rates like any other. I definately recommend gloves if running your hand close to the end, or some sort of stop to remind you...I've seen a few burnt fingers (builds character!). The main benefit I've seen for LE is their confidence with multiple shots. They get more comfortable with 4,5,6+ rounds on target and out of the 2 shot habit. Since they don't get to spend as time and ammo as we do shooting and comfortable with a stock gun, this is where the BC shines for them. I think for those that need it, it is worth the investment & the extra concussion. Of course, there are some depts that are still using FA guns for entries & same thing...not enough time spend behind the gun & they forget their fundamentals at times & the BC helps them stay on target.
For experienced and comfortable shooters, the BC is not a lifesaver. It has some advantages and disadvantages...treat it like any other part & find out if it works for you or not. For those who don't or can't put the time in needed, it still has it's advantages and disadvantages and that shooter needs to find out for themself if it is worth it (and if their team is willing to put up with it). As for me...I see a little difference in my splits on the range. Wouldn't want to shoot it out the door of a sub though....