Eh, I don't think it's really a big deal, takes some heat off me for a few secs in most cases. The WHM I run with uses Fluid Aura (now AST) so having a MCH doing it is nothing new. Sure, you might have to move a bit to get the mob to rejoin the rest, but there's probably AoE anyway. If your people are using it correctly (which isn't always true in the DF) they should be hitting a mob that no one else is to avoid any targeting issues.