Ya' I have to OC my cards to at least 960 on the core to match lightly OCed 470 SLi mins. Even then sometimes I'm 4FPS behind in mins. Below is an OCed 470 beating a 5970 by 5FPS in mins @ 1920x1200 with flippin' 8xAA.
The 5870 in the review can't hit 20 when the stock and OCed 470 are doing 34 and 39 respectively. Definitely poke through the reviews out there and pay attention to mins with AA on. For example, I'd definitely rather 34/55 over 20/70 myself.