Setup: ASUS Crosshair IV Formula, Phenom II 1045T x6, x2 ASUS HD6850 in Crossfire, 16GB Corsair Vengeance (4 x 4GB @ 1600), Corsair Force 3 SSD 60GB x2 (RAID 0), Seagate 320GB (SATA 2), WD Green 1TB x2 SATA 3 (RAID 0), Corsair H80, 6 x 12" high efficiency fans & last but not least my new Corsair CMPSU-750HX power supply.
Replaces a Solytech SL-8850EPS rated at 850W. At present the CPU is overclocked through the bios from it's normal 1045T state of 2700mhz to 3800mhz. The HD6850s are clocked up from 790mhz to 1000mhz. I was having some stability problems (GFX framerates dipping suddenly under really heavy load) and some crashes with the Solytech, but so far the Corsair has worked flawlessly even under continuous heavy load.
I have run all the OCCT stress tests, including the power supply test which maxes out both GPUs & CPU and have so far have had no problems. The PSU didn't seem to heat up very much during this testing.
Build quality seems pretty good and I like the modular flat cable system because it frees up a lot of space for airflow. Unlike the Solytech this PSU comes with four specific 6/8 pin connectors for Crossfire or SLI. The fact that you also have the 8 pin connector means that hopefully when I upgrade my GFX cards I shouldn't have any problems. Initially I was going to have to wait for 3 weeks for my delivery but Amazon updated it and it came 10 days earlier.
Update 6 April 2013
Been using this power supply for just under a year now with CPU oc'd to 3800GHz and not a glitch, so would definitely recommend. As the CPU is not black edition, this means that the whole system is overclocked.