Gosh, why so many MultiWeapons?! Their not THAT great. >__>
It'd be a tie between either a Warlock or Dance Macrabe for me.
For one thing, in the previous games, Wavemasters kicked all kinds of serious arse. XD I mean, I wouldent have survived the game if I didnt have Elk/Mistral tagging along. Plus, magic users have always striked me as the more intellingent an level headed type of players.
On the other hand, like KrulMagus stated, killing people with fans is just all kinds of awesomeness.

I reaaaalllly hope you get Yata in your party, or another Dance Macabre at some point. I'd love to see how their attacks work out. :3
Also, both choices just seems like loads more fun than going around switching classes all the time. It'd confuse me. @__@
Plus, wasen't it stated in Roots that you have to be specail to be able to select the MultiWeapon class?