I purchased 3 of their products in 2014 (2 forends and 1 pistol grip) and the quality was fine but I had major fitting problems with both forends. The first one I purchased, I decided to modify and it worked fine; the second one, I decided to return.
I know you didn't ask about their company but I will give you this info anyways... Their customer service is excellent but I would stay away from ATI. They don't spent much time testing their products before releasing them to consumers. Look at their new X2 Scorpion Pistol Grip, for just one example. When installed, the shooter is unable to push on the mag release button (unless you have an extremely long index fingers) without major adjustments to the firing hand and that requires two hands on the weapon to do. I explained to them the design flaw via email and they replied by saying it was intentionally designed that way but gave no specific reason.