GTX 285 is well worth the 66E over the GTX 260. On a decently overclocked GTX 285, you get approximately 15-20% more FPS than the GTX 280, which is already a few percentage points faster than the GTX 260/216.
FC2 @ 2560X1600, 4XAA, 16AF...
I'm another single-card fan, but that's because 1) My poor PSU couldn't support a GTX 295 2) I don't like that my game performance depends on the quality of nVidia's SLI department.
I'm not saying they do a bad job, but that is a bit too much trust to put in their hands.
Overdrive PC Core2.SLI:
Core 2 Duo E6600 @ ~3.5GHz,4GB of DDR2-770, 8800GTS 640MB @ 621/1836, Western Digital 640GB, LITE-ON 20X, CM Stacker 830, Enermax 620W, Vista Ultimate 64-bit
3DMark '06: 10,302
SuperPI 1M: 15.194s