With a 6800NU you'll probably have to unlock the extra pipes and OC a little to 370/1000 or so to get the same performance. I havn't tried with OGL2 yet, but with 1.5 I could get the same (or pretty dang close) results out of my 6800GT OC (stock 4000 runs at 375 core, 6800GTOC at 370) with the SoftQuadro mod
. The other features aren't so much locked as not used by the drivers. I don't know if any revisions have been made to the chip since then, but mine and other people with older 6800's get the same results.