The 600 cat engine is a very strong, and if it has power valves they're even better. I haven't got to ride an SS but i would like to, with that smart suspension. I haven't heard anything bad about them.
i had one of those. really liked it. got rid of it though because of the smart ride suspension it seemed like a ticking time bomb. i didn't like that the shock was supposed to be rebuilt at the end of every season. guy that bought one same time i did has had 0 problems with it though. the ride was soooooooooo nice. oh yeah did i mention that they have a lot of balls. no problem keeping up the zr 600's, maybe a little on top end, but flat out acceleration that thing was faster then i thought a TRAIL sled would be. hope this helps.
I've logged approx. 5200 miles on mine with only 1 rear shock rebuild. It's due for another rebuild next year. I have never had a single problem with the shocks and they always perform beautiful in light or hard riding. I absolutely love this sled.