I'll sorta echo what the others are saying here.

While it is usually easier to play X of the same class while you get used to the other mechanics of multiboxing, it is in no way impossible for a beginner to pick right up with a mixed combination of characters. Of course it adds to the amount of knowledge and understanding you need to pick up to be able to do it, but if you're not opposed to learning, then I would say go for it.