The PE-750 runs that setup perfectly. Without it, I wouldn't have been able to install the GTX 690 fitted with the Arctic Accelero Twin Turbo 690 custom cooler inside the Define Nano S case.
The PSU itself is actually not hanging. Coming out as a surprise for both me and the Fractal Design rep I talked to about this issue, the PE-750 rests comfortably on those 4 PSU rubber feet. It does sit a little bit on their edge, but it still solidly sits on them. You can see for yourself. Just go to http://www.overclock.net/lists/display/view/id/6530619 and check picture #20