yes i wouldn't be to quick to toss the idea on an inexpensive GP conversion either.
much of the bad press the GI system has got has to do with improper assembly or operator error. say a certain mall ninja type that would have a problem building a AR to start with--if he installed the GP system there will all most certainly be some problems.
i have yet to build an AR system with any GP system. but i have some experience with the ar-18/180s and bushmaster m-17s so i don't see any real reason not to do the GP conversion other than the cost and extra weight- in fact it could be THE solution for a SBR.-no reason it should not work IMHO.