When I bought my Pro this year from Frontier Cycles in Laramie, Dave (owner) actually said he went to the conference and they compared all the sled brand oils along with Ams-Oil for a 1000miles and he said Ams-Oil can in 3rd. The Ams-Oil is good stuff, but will build up on your valves faster than most. Also he said run Arctic Cat Oil would even be better. Being a CAT guy, I have 3 gallons on hand, but I don’t plan on running Cat Oil in my Polaris Pro.
I’ve always ran what oil brand goes with what brand of sled…for the most part any fully synthetic oil is good…
A little off topic, but I always see statements about "Amsoil 2 stroke oil" does this or doesn't do that, but no one states which type of Amsoil 2 stroke oil. Amsoil has several types of 2 stroke oils; such as Interceptor, Dominator, HP Injector, Saber Pro, and Saber Outboard.
And like others have mentioned, use what you like as long as it meets the criteria that the manufacturer has set for your sled. Lots of good oils out there.