Still to be proven (in a mnt sled) and the motor is the only thing different, with the added power its likely to wear out the other parts faster too. The only advantage would be if the resale value was to hold and so far the yami's havent so its a wash other than the weight. My twisted 800 has gone 3 seasons and is the most reliable sled I've ever owned.
The bottom line is that a 4 stroke engine is commonly going to be more reliable than a 2 stroke.
I acutally am very surprised the weight difference is so big. I weighed a yamaha turbo vector engine last year compared to a rotax 700 twin and I ended up with only 60lbs difference, once you weighed all the components. I think it looked something like 180's on ethe 4 stroke with turbo, header, downpipe, clutch, carbs, intercooler, oil tank, wiring. And right at 120 for the 700 twin rotax engine with carbs, airbox, wiring, clutch, pipe, silencer.
I have a hunch that the silencer on the m1100turbo is going to be a very good way to cut alot of weight. I am guessing in that 20lbs range that people have said. I know this can be cut from the m800 as well, so no flaming me on that!
Can anyone post up real world weighed weight of the m800? Just interested to see a comparison.
I myself am not worried about the weight i am pumped to get my 4 stroke turbo.