the XFX is also a great choice, I have one and it has been rock solid. Keep in mind that you could also get away with a 650w but if you have the budget you might as well spring for a 750w unit to give you some headroom to oc the gpus and that beefy cpu.
The corsair unit I listed above is also a rock solid performer, either of these units will be more than adequate for your system.
imo no I believe the XFX unit is a seasonic; they are definatley on par with each other performance wise, like I said either is a great choice. neither are modular so I'd probably go with XFX bc its cheaper AR def a good deal!