I'd say give the Infinity a go.
You know exactly what your getting with a NF7, most get stuck around the 220/230 mark, the latest ones being mostly poor performers. If your willing to mod it, then you can get more from it.
But the Infinity, the new kid on the block. Lots of people are hitting 240/250 a few 260/270.
Theres some signs of poorer 3d performance with cards other than ATI but this may be fixed with a new Bios.
Talking of Bios, DFI and in particular Oskar Wu, theyre Bios expert (ex Abit) is working real hard on them, and is active on a few other forums.
When are Abit going to sort the NF7's Bios ? I'll tell you, never.
I've got both NF7 and Infinity, my NF7 went up to 223x11, still working on the DFI, but its running Prime right now at 245.
Anyway, you can guess my vote, DFI.
I'm surprised theres few of them here.
TDF.