because the 10speed cassette fits on a 9speed free hub therefor the gap between cogs is more narrow
Okay, how about this then.
I rode an XC bike with dyna sys XT 10 speed the other day and I loved the shifters. I like that you can shift up 2 at a time and I liked how it felt. Does 9sp XT have this feature of being able to shift up 2 at a time?