I've been trying 13.8b on my single 7970 in Crysis 3 and at the same time I'm attempting a no cloak, armor or suppression run on Post Human Warrior, which technically SHOULD be less lag prone since cloaking adds more graphics effects.
If anything it should run a bit smoother, but so far it seems a bit more laggy. At the same time I'm trying the built-in MS HD Audio driver, vs the Realtek HD, but I doubt that's what's causing it since it's just a S/PDIF pass through to my AVR. Going to try again with the Realtek driver, but if it still seems laggier I'm rolling back the GPU driver.
At first I was stoked that AMD were cranking out drivers more often, with some pretty good improvements in games like FC3 and TR 2013, but lately it just seems like they're getting ahead of themselves. 13.6 hasn't even gone WHQL, and all of a sudden now there's 13.8 beta released before it even seems ready for consumers. The games Hardware Heaven tested it on saw little if any improvement, some actually had worse results.