I'd be curious to see if microstutter is more noticeable visually on 120hz displays. I must say I noticed it quite a bit with my old 4870x2 and to a slightly lesser extent on 2 260s but this was only at 60hz. I personally enjoyed Crysis more on a single 260 than a 4870x2 interestingly enough and I'm confident the microstuttering was behind this.

Like has been said its not that noticeable at higher framerates but in games which are more taxing ( ie the types of games where multi gpu setups would be most desireable ) it is much more noticeable.