Well, according to the ATF, PWA produced 2,964 rifles in 2000, and 2 in 2001. No more after that, as you said. Only you and 2,965 others have something like what you've got, if it's a factory-built rifle. That statistic is representative of complete rifles only, not lowers or builds. Which is yours?
I don't know many companies outside of the big manufacturers. Colt, Bushy, Armalite, DPMS and Rockriver Arms are all top-notch, with many smaller firms close or matching (companies like Ameetec Arms, Stag Arms, MEGA, etc).
But ultimately, if your lower reciever is forged alluminum or a quality casting with quality parts (trigger group, bolt catch, all that stuff), it'll last you years.
It's all completely modular, too. You can replace any and all parts now or in the future as the need or want arises. Different trigger, new set of springs, new forward assist, whatever!
My point is, you can make your AR solid gold in terms of quality if you don't feel that it's already there. It can be done pretty cheap too. If you ever need a part, big or small, go to www.dpmsinc.com
and check out the online store. DPMS is one of the chief manufacturers of AR parts in the entire industry, and has been since the 80s.