A lot of people say the 165 feels as agile as a 153. The one thing that no one has mentioned yet, bigger drivers and bigger wheels will make less track be on the ground.
In our experience, switching to a 10” wheel leaves 2” less track on the ground. So, going to bigger drivers and bigger wheels could make the sled feel 4” shorter. That’s almost the difference of track on the ground between a 165 and a 154.
I may be wrong, but I’d love to have a 18’ and 19’ Mountain cat and alpha sitting next to each other and measure them up to see what the difference is.
Cat went from a 162 to a 165 with the 3.5" pitch so the foot print is probably pretty close to the same there. The 153 to 154 might have lost a little. The flex of the track might makeup for lost footprint in some situations.