I've now got 5 physical authenticators.

At the moment, I can use one to simultaneously access each of my 5 B.Net accounts.

If you can always use one to access all 5, then its 4 x 6 and change wasted, which isn't much.

If they change it so one authenticator can only do one code then its done (instead of one per B.Net account), then I'd need to use all five, but that's still a lot faster then a 30 second wait between accounts logging in, within the same B.Net account.