I have an 07 Summit 151, my lady has 2010 Summit 154. Her 2010 pulls harder and can climb better, as the snow gets deeper it pulls even harder. Her's is an X model and rides like a dream through the bumps.
The extra pull is nice and Im not sure why it pulls so much harder, track is only 3" longer and with electric start I think the 2010 is only 15-20lbs lighter? Both have 151 horsepower I think.
That all said, i still like the way my rev rides, I can huck it around more and find it easier to side hill. I do have more time on the Rev though so maybe Im more comfortable on it?
I was asking myself the same questions this year and waited to see if I fell in love with the GF's sled, but I didn't fall head over heels so I have decided to keep the rev and put some $$$ into it.
First, new skid, Im thinking the newer skid geometry is partly why it pulls a little harder and floats/climbs better. I have bought a 2011 skid to go in off an X complete with shocks. Then Im going to do some fox floats up front.
Hopfully I can get the rev to pull and float like the XP, would be embarrassing to have to borrow the GF sled on big powder days.