How much steeper is the learning curve between 3 or 5 toons?

I have another dual core rig (single vid card) that can be relocated to my desk area. If the 3 goes well, I am open to the idea of 2 more accounts.

How well do hunters do? I would think there might be dead zone problems. Has anybody ever tried 4 or 5 shadow priests?I've never leveled any of the ranged classes. I've got a 61 priest and was very good with him till BC hit, but I'm sure a 'boxing' priest and a single priest have very different playstyles.