The P9X79 Pro is a great motherboard it's not much different than the Rampage IV Formula (I have both), Rampage just has a plethora of extra bios overclock settings.
If you're watercooling it's easy to get EK waterblocks for the VRM's with Asus boards, throttling because of hot VRM's is one of the main issues with X79 if you overclock heavily and run CPU heavy software, I'm not sure if the Sabortooth active fan resolves that.
Thats my point, I am going to hit high temps before I need those extra BIOS settings.