They used to have some numbers on their website in the support section a few years ago, but looks like corporate scrubbed all that. Probably in the name of efficiency and everything has to go through email for service requests now, and push people to go to the distributors for sales questions since they don't sell direct. Calling BBA or the guys at Ice Age might be your best bet on performance or fit questions. Carver Performance is also good. They are pretty XC racing focused, but have been helpful for me on the Cat side figuring out custom setups. Otherwise, all the snowmobile development for Fox is handled out of their service center in Minnesota. If you could talk to anyone at Fox I would try to get in contact with someone there.
My $0.02 on air vs springs:
In general the air spring design seems to work well for larger or more aggressive riders that benefit from some extra hold-up and bottoming resistance. Or those that like to tinker and tune to get their setup just right. Air sleeve maintenance is key to reducing seal drag and maintaining low speed plushness. I clean/re-lube every 500 miles or so.
Springs are a little more plush and the set it and forget it crowd like not having to check air pressures and do air sleeve Maintenace.
Air used to be lighter, but with the latest versions of lightweight design on components and springs along with Evol chambers and negative springs on the air shocks I wouldn't be surprised if weight was now a wash.