I've been discussing this a lot recently and hand size does make a difference on jamming routes. Especially some of the classic grit ones.
We were trying to come up with a list of routes that girly/slight hands can jam and whillans meat fists can't. I find that gold dragons/camalots are perfect hands for me (and my hands aren't that large) whereas my girlfriend gets bomber jams on red to greens.
The crack in the corner of Laugh Not (HVS 5b) seems to take hand jams for little hands, as does the back of the groove of Mean Feat (HVS 5a) and I've wondered about the initial crack of Valkyrie (HVS 5a) as its red and green cams in the back.
Any thoughts or suggestions?