You don't buy a $200 card to play games on a $700 monitor.You just don't.You also don't buy a $350 CPU to pair it with a $200 card.You should get a custom GTX1070 like Gigabyte G1 when those come out.Better yet buy two of those in SLI to truly do justice to your $700 monitor and $350 CPU.
I don't quite agree. I got a 280X when thy got refreshed alongside the 770's for $350, then scored a super good deal for 2 of them for $250. CF IMO works well, but like a previous poster said, it really depends on when the game or drivers optimizes it. Overwatch beta wasn't optimized for AMD at all, running 80 FPS on ultra @1080p, but @63 degrees on my card.
Now I think I run 160 FPS at about 70 degrees on overwatch.
Now back on topic, I think the 480 is the best purchase option if you're stuck on options. For price/performance it's pretty good - however, I would not crossfire it yet. With DX12 and ?async compute (I forgot what it was anandtech was testing) you can mix and match video cards. I'm not sure what AMD's plans are for CF over PCIe, but that'd be golden if you could do mixed AMD cards for CF before or when DX12 comes out. I'd probably get one 480, and mix it with the top AMD card when it comes out