I have personally owned the S27A750D and I can say that it was a very very nice monitor. There are some things you have to watch for though before buying it:
It is a glossy screen, meaning the screen is very reflective in lit rooms when viewing dark images. I had an outerspace background and I could see my entire room reflected in it. If you play in a very dark room, or if reflections don't bother you, than you'll be OK.
It has a known problem where it will randomly shows a blank screen with the words "Not optimal display settings, please use 1920x1080" and forces you to either turn the monitor off and on again, or unplug and re-plug in the cable. This doesn't happen often however, maybe once every 6 hours.
Be warned that all current 3D 120hz monitors are TN panels, if you want something better, you'll have to resort to 60hz monitors.
Other than that though, the monitor is great, it has a beautiful glossy black finish on the stand and bevel, and the 120hz is very nice on the eyes. You will definitely notice it at first for a while, though I personally have switched back to a 60hz monitor and it didn't really bother me. Your eyes will eventually get used to it either way and you won't notice it much anymore until you switch back to a different hz.
EDIT: Nevermind, I failed to read your setup, you should have no problem gaining at least 120 frames in just about any game Nice rig