I never understood the driver complaints either. ATi or AMD worked for years here, and I had a ATi from the 9600XT era till this day. XFX is known (and a few others) to skimp out on certain parts. There are vendors that dont take AMD's initial PCB design and kind of cook one of their own, with usually cheaper parts. Thats why some of the cards are usually a few bucks cheaper then the other. The downside is usually the worse power delivery which can cause BSOD's, or simply restrained on overclocking for example. Not that it matters now anyway, since chips can automaticly boost their clock(s) according the workload, but it was different back then.
With buying ATi, AMD pretty much had all the IP ATi had and we see that in major consoles and PC's these days. They are able to bake their own APU's and perhaps in the future a APU with it's own HBM memory.