They tested Crysis (almost one of the worst scaling engines going). 4870x2 is not really a 1680x1050 card. Needs 1920x1200 and up to really shine.
I totally agree. If I wanted more power at 1680x1050 and I had more than $300 to spend, I would opt for the GTX280. Faster than the 4870 and it's $140 cheaper than the X2. I know I would not really appreciate the 4870X2 at 1680x1050. It's not that it's not worth it but realistically it is not for 22" screen users. It's for the 24" and up crowd.
For smooth game play (nearly always over 60fps) in all but Crysis, I think it goes something like this...
19" - 1280x1024 = 9600GT, 3870, 8800GT/GTS's ($100 - $200)
22" - 1680x1050 = 9800GTX, 4850, GTX200's, 4870 ($200 - $400)
24" and up - GTX200 SLI and 4870X2. ($500 - $800)
Reviews should really point out where the $500 and up solutions shine. Not this 1680x1050 and lower stuff.