Looks like the dev always recommends a full wipe. However some folks on his thread at XDA have stated they flashed over with no problem.
If you want to try it, make a nand backup, wipe dalvik (but not data) and then flash. If your phone gets wonky (sorry about the highly technical jargon) then do a complete wipe and reflash. If it gets REALLY wonky you've got a nand backup to fall back to.