I am also a numerous time user of SLI and Crossfire, had no troubles with either of them to be honest though I do think the people who use 'high-end' cards in dual set-up are a bit deluded as it is essentially pointless for almost everything except benchmarking.
the whole point of SLI and Crossfire is mid-range, or at least that is my interpretation of it. right now two 6850/7770 cost significantly less than a GTX 580 but perform similar or better in a ton of circumstances, also produce less heat and consume less power (especially the 7770 Crossfire).
did in the first time with two 7600GT, which were mid-range cards at the time and got 7800GT or higher performance for less cost, less power consumption. also mid-range cards tend to be shorter than their high-end brothers for people with length restrictions in their cases, also microstutter is massively massively blown out of all proportion, using a Crossfire set-up no and get no obvious microstutter in anything I use it for but still gives strong performance.
to sum up my personal opinions on Crossfire and SLI, want 'the best' then go for the high-end single card solutions, want best 'bang for buck' go for dual mid-range cards and get similar/better performance for lower cost, no brainer.