R9 280X is a rebadged HD 7970. (Tahiti XT)
R9 280 is a rebadged HD 7950. (Tahiti PRO)
R9 270X is a rebadged HD 7870. (Pitcairn, dubbed as Curaco)
R9 270 is a stripped down R9 270X that draws less power and requires one less PEG connector.
So, basically, most of the R9 series of cards are just rebadges of HD 7XXX series of cards. R7, too. The only new chips that came out with the R9 series are the R9 285 aka Tonga Pro, the R9 290 and the R9 290X, aka the Hawaiis.
I don't know where you're getting this hardware issue from, but the HD 7XXX series of cards are stable, it's the OpenGL support that sucks.
AMD drivers require clean installations, btw. Something a lot of users neglect or are unaware of the procedures. This can have unwanted consequences if you just keep on installing one driver over another.
And there're a couple of more tricks that I use. Lets assume that OpenGL Vsync is broken with AMD Catalyst 14.10, but works fine on an earlier version of Catalyst driver. We take a the ATI's OpenGL dynamic link library files from the previous stable Catalyst driver and place them with the OpenGL game executable, and voila! Problem solved.