Another benefit might be gearing up in instance runs, no more fighting for the same gear x4. I'm still working on 4sham+1boomkin for now as I'm still new to multiboxing/macros I do however have a nice selection of 70s so I might swap a couple shamans out for something else in the future...who knows.

Keep us posted on how your team is doing and I'd love to see how you've mapped out your keys.