Set this up with some guys in my company and we're giving it a try today. So far, after going through the interface quite a bit, I decided that it's kind of confusion to reason about who is going to be called when. For example, you have timeouts for escalation and timeouts for consecutive notifications - at what point in your notification chain for a specific user does the escalation happen? Is it only after all types of contact have been exhausted? Or will secondary on-call be notified after the admin-settable X minutes (default 30) no matter what primary does?