OK, a 15 minute refresh could be a deal breaker. Our monitoring system notifies us after a 5 minute outage. If we 'hit the cycle wrong' it could take another 14m 59s before the Droid gets the email. That could be 20 minutes of downtime before an email notice.
I'm very surprised that the Droid does not use IMAP IDLE. Even our 'self hosted' email (via IMAP) shows up within a minute or so on the Berry.
Yeah, that is annoying that there's no IMAP IDLE support yet. How were you handling the notifications before BIS supported IDLE? (I think it was introduced in Sept. 2008)
You might want to consider putting a small script on the monitoring system to send a text message via the Verizon website (that way if e-mail is down you can still get notifications)