I use them all the time. My 2 cents?
Cons: I agree that they can be hot. If you order them sized correctly, they are tight, but that actually helps [after you get used to it.] They're not really cheap, but not really expensive either.
Pros: It works. It conceals full size autos, my PC 327 and other big revolvers, and has two pockets. One for the semi, the other for extra mags, or a revolver and BUG, etc... and it all works well. I usually carry an ultra-compact 9MM, and forget it's there. I have to disarm frequently during a normal work day, and access is easy while not drawing a lot of attention. No holster to remove from belt or put away.
You do need the quick access Oxford or short sleeve shirt, though. I'm not inherently cheap, but my wife saw the ad online, and converted some of my dress shirts to work with the 511, and it's a perfect solution.
With coat and tie, or just the shirt, tucked in, you look absolutely "normal." Never been tagged, even by others who are carrying....
PS, I don't have any vested interest in 511, it's just a perfect CC solution for me, and it has proven itself for a couple years now.
Len