I have only upgraded to BC on my 5 RAF accounts and now am glad I did. I can only reach level 70 so this gives me the opportunity to get everyone exactly to 70. Hate when one or two end up being off as far as timing of hitting the next level.

5 hunters to 70
5 shamans to 62
5 rogues to 60
5 locks to 60
5 pallies to 60

Then need to get druids and priests to outland next. Dropping my warriors and may drop my mages.

Once I get caught up to 70 going to upgrade to lich and hit it hard. RAF should be quick going there.