I'm with you on this.
I'm increasingly becoming disillusioned with multiple cards. I've had SLi in the past and currently in Crossfire with two 4890s. Tbh, I don't think the extra expense, fitment and cabling - not to mention power draw is actually worth it. So few games actually fully utilise the power of both cards concurrently and what benefit is gained, is usually blown out of the water by a superior, single card as a replacement.
The fact that ATi can't enforce V-Sync (which is a 100%-of-the-time requirement, imo) while enabling Crossfire is just silly. I've done multiple tests recently where a game appears smoother running on a single 4890 than when Crossfire is enabled. Put bluntly, the next upgrade - like yourself, either nVidia or ATi - will be a single card for me.
D.