I have a 2012 Adventure 600, and only really kept track on a couple of tanks during my first trip to the UP, so the motor was brand new and not broken in. I was getting 12.5 mpg and the group I was with rides very hard! I did not measure any oil consumption, but it sips the oil to the point that rp7x is all worried I'm not using enough. I just turned 1,000 miles on it this weekend and the engine is so smooth, I just love it. Plenty of power too! You really can't go wrong with the Polaris 600, it's proven itself for many, many years.
In all honesty, the eTech gets better mileage, as I ride with one quite often. However, I prefer the solid feel of the Polaris vs. the light weight of the Ski Doo. Something has to give to get that light weight, and it's usually parts you don't want to give!