Ive rode them all. Lynx, expert,matryx 850, 9r and boost. Daughter has 600 catalyst. Riding 858 this week. Only thing i haven't rode, and could've or should've, is freeride 146 turbo. Looks like a hoot.
I can't tell you what to buy. It is all preference. The catalyst is the easiest sled to ride and i dare say the best balanced. It doesn't have any of the bad ascender alpha traits that i can see. I would say in some ways it is more similar to a matryx because of steering and some ways similar to doo or lynx on rolling it on edge. There is no break over like polaris. Drive it with feet in deep powder. Still easy in lesser snow. Doo and poo get a lot heavier feeling. Obviously the catalyst does too but it is just so much easier. Catalyst rides at least as good as the matryx on trail. It is not going to ride as good as lynx or doo. The old alpha was the crappiest ride out there by far. Doo turbo r is my favorite motor. No idea on 858 but no factory turbo. Polaris 155 kaos boost with 325 track is one of my favorite sleds. Also 9r in same configuration. I should say minus the crappy brake. Don't like expert spindle and skis. Twitchy, to me, in certain conditions. Mentioning these so you know where I'm at. Take this all with a grain of salt because you really don't know how i ride or what i like. They all have their pluses and minuses.