I quit paying attention to them several years ago so they could have stepped up their game recently. The TLR-1 and whichever one has the built-in laser. The laser version was used by our SWAT team and they were always complaining about them not working reliably. That was on a mix of plastic and steel framed guns. The TLR-1's were on a few AR's on our squad and no matter how tightly they were installed on the rail they would fly off under recoil. The guys I saw this happen with were both squared away and not your typical LEO who just shoots whatever they're told.
I may try one down the road but have several X300's and they are no where near in need of replacement. In fact my first one now gets used and abused in classes and matches. I'm waiting to see how long before it does and I've been using it since 07 or 08.
I thought I had a pic that better showed the wear but this is the best I have for now.