It's a superb combo on hard packed and dry trails although the rear is abit 'interesting' in the wet. You have to careful when putting the power down on climbs as the Crossmark can slip abit. In the ludicrously long run of dry trails around here in Bristol it's been great.
The 2.35 and 2.25 are about the same in width. I initially had a 2.1 Crossmark on the rear but that felt abit fragile so went up a size.
The Zesty isn't my only bike so gets used when conditions suit the tyres!!
EDIT: Cynic-al…you're right except these are UST wheels so you may as well run UST tyres on them.