Anyone can get a decent idea of what to expect just by reading these forums - the Sager 9860 first shipped with the lower-clocked 6800go (they referred to it as the DDR2 version and said it was clocked at 250/300(600) which sounds odd - the memory clock is about the same on the 9300 but the GPU clock appears boosted just a bit if it really is 290). From all appearances, it seems that with the 6800go you have all kinds of choices as an OEM like Dell as far as how you want to clock it, cool it, etc. Obviously an effort by nVidia to make their part less "cookie-cutter" and give OEM's room to boost benchmarks here and there.
At least that is my theory.
Anyway, one thing we know for sure from both the Sager and nVidia's own website is the version with GDDR3 is clocked at 330/500(1000) which is clearly much faster than the one posted here.
You can see benchmarks of the "old" Sager 9860 with the DDR2 6800 here: http://notebookforums.com/showthread.php?t=58703
The benchmarks for the GDDR3 version (remember, it's still not the Ultra, which is clocked at 450/550(1100) - that is a hefty bump) are here: http://notebookforums.com/showthread.php?t=62285
Granted, those are Sagers using desktop processors and the DDR 6800go appears to have a lower GPU clock speeds, so performance won't match the Dell's; it does however give a good idea of the difference between the two versions.