I don't know if they've made any additional headway since the latest GPU core for AMD/ATI ('GPU3'), but, with that one, on Radeon HD 5000 series (or later) hardware, it's better than it used to be, even if it's not as great as I'd like.
I can get ~3500-4000 PPD from the 5670 (400 stream processors @ 775MHz) in my HTPC, and ~3000 PPD from the (mobile) HD 6570M (400 stream processors @ 650MHz). I run the v7 Windows client with the GPU slots set to client-type: advanced. If anyone reads this and can suggest a better configuration (outside of overclocking, both those machines are hot enough as is), I'm all ears!
For comparison's sake, I get ~4000 PPD out of a Nvidia GT 430, which, on paper (and for gaming) is a much weaker card than the 5670. Plus it looks like (if I get lucky WUs), the
new beta projects with QRB could bump that even higher. Stanford says they are planning to implement QRB for all GPUs eventually, I think, so that could help GPU points across the board.
Since GPU3 is only for 5000 series and higher (
more info on GPU3 and AMD), that means unfortunately my two 4870s can't use GPU3, and I can't justify the power consumption of those juice guzzlers for even weaker results.
Hope this might help you make the decision, one way or the other!