If you use only one worker name under one address, you won't have a direct way of knowing which machine is producing v. the other...what condition they're in.

I enter each machine as a separate worker under my username, but use only the one BTC address for payout. That way I have a direct way of monitoring production for each machine without necessarily relying on an outside app.

I run ~40TH over seven machines, and each can be monitored separately.