I've had seat time on the Axys and the new 850 Doo.
I am a Doo guy and after spending 3 straight days on a Poo last month and then riding the 850 Doo right after, I realized how good the Axys handles in comparison to the 850.
The low end grunt of the Axys and the lightweight chassis makes it shine for technical riding.
The torque of the 850 is incredible and the improvements over my XM are all very nice!
That being said, I snowchecked a 850 Doo for 17 mainly due to the longevity and reliability of the ETEC engine. Even my buds 2016 Axys had all kinds of Electrical problems this year which deterred me from Polaris.
2017 is going to be a fun year no matter what you guys choose!