Built the upper in 14.5, mine is predomnantly on a Bushmaster lower.
Personally Iove it, being able to adjust my gas system to if the can is on or not makes life easy.
The most common complaint I hear is that the gas block is "large and bulky blah blah blah", I personally like the fact that it lines up PERFECTLY with my DD Omega 7 rail so I can mount the ATILLA all the way forward so my thumb switch mates with my grip PERFECTLY!
My only complaint is that without using a lighter spring my ENINDINE buffer would short stroke keeping the bolt from locking to the rear on an empty mag when running without the can, it worked just perfectly in every other way with the enindine but was spotty on locking the bolt to the rear without the canm. Now that the H2 is in, it functions flawlessly regardless.
If I knew how to upload pic I would, but sadly, I seem to only be good at shooting guns, not pics. If you need a pic feel free to PM me with an email and I'll shoot you a picture.