Need clarification on if that's a 600 ace or a 600 EFI / Etec. There's lots of 600s and they go from 60 to 125 hp...
My backup / family sled is a 900 ace, and I'm going to see about swapping it from a 600 EFI or 600 etec. The biggest issue by far with the 900, no matte who rides it, is the "digital throttle". There just ISN'T that connection between your thumb and the engine, and that subtle delay can be downright dangerous for any newer rider. The weight over the skis and relative lack of handling is a somewhat close second on the 'downsides' - almost everything else is pretty damn phenomenal. No maintenance, lots of adjustability, can be relatively docile in eco or boogy pretty good in standard.
But seriously, the throttle is a major issue. Every single person I've taken out on - except my one friend who's very experience, and myself - have had minor accidents with it. EVERY. SINGLE. ONE. The throttle is just too jumpy and unnatural in standard mode (nevermind sport, which is basically binary). Everyone has to resort to eco mode, unless we're on a lake... and they end up switching back and forth all day. Almost always, I offer to let them try my 850 somewhere safe. They're terrified, because they don't trust the 900. Then they try the 850 and it's somehow twice as powerful but also twice as predictable - and they prefer it. So yeah, looking to trade it.
The 600 ace is, IMO, a glorified lawnmower. Amazing little engine if you take the scenic Sunday route, but it just doesn't have the jam to have fun for most people. 600 etec is an incredible motor and I almost miss the older one because it was a little lower on power and little better for new riders, but the new one is still great. Haven't ridden a 600 EFI and the rest of the sled is somewhat seriously downgraded (which is a similar issue with the 600 ace) - no good shocks available, not even a good skid, etc. Part of me wants to get a nice 600 Etec X package sled, and swap in a 600 efi...that would be the perfect backup sled IMO.