The B3D dudes have talked about it a long time before, IIRC during/before the G92 launch period.
It's hard to compare to ATI at that period because the 3850/70 were bad performers with AA on, and only AA would tax memory usage extensively enough to limit you to <1600x1200.
At raw speed tests it's harder to determine, but there are still cases where the 256MB on the 8800GT runs out first compared to the 3850.
http://images.anandtech.com/reviews/...2/vsATI-qw.png
There are also cases where the 8800GT 512MB flat-out dies off at 1920*1200 8x AA while the 3870 still holds on, although not very playable. I think this one can be referred to in the Computerbase tests.