While climbing ability is important, so is stopping in the steep. Wife's 03 600 RMK switchback 144x1.25 did fine most the time although it did give up some climbing ability. BUT - coming downhill with that track on steep hills was bad. She had told me it fishtailed and felt like it wouldn't stop but I kind of wrote most of it off to her being a relatively new rider. Until my sled broke down that spring and I was using hers and riding with my buddy. Coming downhill, same path, buddy got slowed down and turned onto the trail, no matter what I did I could not get her sled slowed down enough and went right on down the other side below the trail... luckily that area was open too and when I finally got stopped I turned around and rode back up. But it was not a good feeling. Within a month her sled had a 2" track on it. Made a world of difference.
So if you want to give up a little in the flatland speed department for better climbing and braking, make the switch, add scratchers for those icy or snowpacked rides.