MoF ReimuC is outclassed by ReimuA in almost every way, since ReimuA does slightly higher damage to bosses on average, while having much better stage coverage. The only situation where ReimuC is better is if you can pretty much point-blank a boss, which is only possible with a few spells, mostly on lower difficulties. At least that's my experience from trying ReimuC in one of the MotK tournaments.
It seems that almost every spread shot ZUN makes is terrible, actually. Except UFO SanaeB, who's a bit overpowered instead. I wonder if spread shots are just hard to balance.