I like to see a full spread of games bench between the GTX460 vs. HD5870 (both OC to max) before I can make that judgement.
IMHO, at max OC the bench gap between the 2 would be quite narrow.
Maybe Anandtech can pick this up and do a complete test/OC article.
Cant you do this in ANANDTECH under bench (minus the OC)
http://www.anandtech.com/bench/Product/162?vs=180