I could care less about the altimeter, but I might if I didn't always have my GPS on hand, but the gage itself is allot easier to read while moving. If our trails were always smooth, the telescoping handle bars would be sweet, but since our trails are usually trashed, I just leave my bars high as I am always standing up over the rough sections.
The floats are awesome for taking big hits while still being soft for the little stuff, but they are not as good for high speed stuff as mentioned before. They are much tougher though. My wife bent here mag side a-arms early this season and it wasted the shaft on her standard shocks. I put my Floats on, and she did it again on our last ride! The floats didn't bend, but the a-arms were bent much worse than before.
The two biggest reasons to get an 09 are the engine reverse and the powerclaw track. But if your going to get an 09, you might as well get the 10 so you get both + another 10% more HP.
I barely see a reason to get an M1000 unless your going to get an older one for a good price. The 2010 M8 is d@mn impressive, it doesnt have the legs my M1000 does, but its lighter, and just as fun to ride.