honestly the ROG is kinda lame to me especially if you have to pay considerable price premium for t. The extra memory is useless since games never pushed memory that high.
GTA-IV makes use of that extra memory, and if you max Textures in Crysis, or add texture packs to Oblivion and such, you can easily push past 1GB of VRAM per core.
The cores are the same just with better cooling so their can reach those higher clocks. You can clock one even faster with liquid cooling like mine.
But you still don't have the power circuitry behind that, so liquid would take this even higher.