first video isn't microstuttering; it's frame buffer or load, when i had a 3870CF setup i never noticed microstuttering but i noticed gains in fluidity when switching to a 4870 which was just as fast in properly optimized titles and faster than the CF in unoptimised titles...

however CF does give you noticeable performance gains (just take a look at the frametimes you postet; even the slowest frametimes of the sli setup is better than the basline; average fps suggest that you get a 90-100% gain but using frametimes you get a worst case increase of around 50-70% which is very noticeable in alot of games; i say that a 30fps single setup feels better than a 35-40fps CF setup in some games which suffer from MS (not all games create microstutter); but when properly optimized a CF setup is 70-100% faster than a single setup so you won't notice the uneven frametimes...