TRI sli scales very well now and the FPS is quite steadily high on all the games I play, the only time It stutters is if I'm using 3 screen surround resolutions and I put the AA up too high, I can actually run out of VRAM, but otherwise it's smooth as silk.
In crysis 2 I get the same beautiful 90+ fps average, (with the lows being in the 70's) but the flickering shadows have put me off playing till it's fixed.