Eh, so these numbers show that bandwidth has nothing to do with the achieved multi-texturing fillrate (and in fact I think that's rarely the case for most cards, at least without using float textures).Actually, looking at the "spiritual" predecessor of G92--the G84--it seems the bandwidth is the key here, but not only:
G92 (8800GT) -- 57GB/s, 75% out of 33600GTex/s theoretical fillrate;
G84 (8600GTS) -- 32GB/s, 70% out of 10800GTex/s theoretical fillrate;
8600GTS has more than half the bandwidth of 8800GT, but achieves less than a third of the multi-texture fillrate.