Although, it must be in limited supply. So, barring that, I've considered something along the lines of SLI XFX Radeon HD 7970; although, something like that seems foolish considering how close we are to the next series coming out.
All things considered, I'm assuming the 7990 is the response to the 690, so I can't really go wrong with either card.
Aside from those things, I'm curious about the driver/bios headaches that may result from such a build. Is that common? Every computer I've built has always been using components after they've been out for 6-8 months and even then there's sometimes stability issues while stuff gets ironed out.
Am I looking to greatly magnify such problems (or others?) when doing a build like this?