I suggest you give Tim and Rusty at Coastal Victory/Hotvic.com a call (843)651-9799. They have been putting 21's, 23's, and 26's on the front of XC's for a couple years now.
I have ridden each & every bigger wheel & rake combo they sell & install. one thing you need to consider with the 23 & up wheel is adding bump stops in your forks. they prevent you from slamming your fender into your fairing if you hit a pot hole or need to do some emergency braking.
If you do a lot of riding on curvy roads, a 21 or 23 with a rake kit will still handle great and ride smooth. Personally, I ride a Vision with 8 degree rake and a 21" wheel, she rides smooth and handles great in the curves. I wish I could move up to a 23", but to do that I'll need to modify my headlight, and I'm still too chicken to cut up such an important part of my bike.
I hope this was helpful, Good luck.
2008 Vision Street
Custom paint; tinted turn signals; Lloydz cams, timing gear, PCIII; Hot Vic 26" Windmill wheel, billet wedges, tips, pegs & covers; Focal IC-130 5.25" speakers, Arc Audio KS 125.2 BX2 AMP; Hot Tails custom seat...
2012 High Ball
Custom exhaust; high performance air filter; Hot Vic sissy bar, lowered 1.5" rear, .5" front; Witchdoctor 2" peg extensions & pegs, Hot Tails custom seat & passenger pad...