Nice system.
I still think the bulldozer idea is a nice one, if not for me.
To be honest, the HX620 is a solid bet if you can get it to run both cards. If not and you want to save a bit of money, I'd try the MM. I picked up my HX650W off of the MM over a year ago now for about £60-70, and I think second hand prices are now at around 50-60. So it might be an idea. The AX PSUs also frequent the MM quite frequently at good prices. Only problem of course would be you'd have to buy a new set of braid, which I know from experience isn't cheap xD
kd