I set up my bnets last night and everything is fine. I have 6 emails (one per computer) and 5X7 accounts and 1X1 account for 36 total.

Although you use Bnet email as your log in you still see your old account name so everything is basically the same as before. You still can see your old account name from a drop down list and you use that to access your account and what not its not that you lose your old account name.

I set up all 36 of my raf's with one email, when I did it.

Just think of bnet as a "master account" with your current accounts as "sub accounts", you still use your current account names.