Hello,
I have never fired an AK-USA model, but I do own a Krebs AK-103K that is just awesome! I don't know how many rounds I have put through it, but I can tell you I have fired it almost every weekend for the past 3 years with a minimum of 120 rounds (4-30 round magazines) I have babied it, then neglected it, then babied it again, and it has never let me down. It eats Wolf, Barnaul, and other Russian surplus ammo like Rosie O'Donnel at a smorgasboard, and is plenty accurate out to 200 yards. I have a Kobra sight for it as well, which makes a fine battle rifle even better. Whenever I bring my AK-103K out to the range, it always gathers it's fair share of onlookers. The trigger is smooth, the fit and finish is top notch, and feeding 7.62x39 to "Masha" is not an overly expensive proposition. I have a Russian friend who is a former participant of their excursion to Afghanistan, and was a member of a Spetsnaz Company. He is impressed with my AK-103K. That alone for me is a good enough endorsement. Hope this info helps you.
The only thing I would like to add to this rifle is an integral forend light. Something like Surefire offers for the shotguns. With a pressure sensitive pad, or a dedicated on/off switch.