Yes the nVidia submitted kernel is expected to run 10-20% faster than Dave Andersen's kernels.
*sigh* I was almost hoping that was not the case. Now In good consonance I can't leave it be and only hash @ 500 kh/s a card.
Back to fucking this some more.
500 is fairly good on a Titan without overclocking. I've got my solo titan at 620 with +155 Core -502 Mem, try it.