They sound like they should be talking to David Blaine
if it's magic they are after.
Delays are still apart of life, even with a BES sometimes.
The 15 minute poll time on the Web Client only means the delay is usually up to 15 minutes and is dependant on when the e-mail is sent during that interval. So, in many cases the email can be on the BlackBerry within minutes of it being sent.
Of course you still have the desire for multiple e-mail addresses on the Blackberry, they are aware they can only send from one e-mail address?
If forwarding is allowed on their mail server a single account could be set up to catch all e-mails forwarded from the receiver e-mail addresses and then forwarded to the BlackBerry.
If you are only setting up one device there is no need for VM but for a few, why not? it should work.
When potential BlackBerry users talk this way, they generally do not fully understand the value BlackBerry e-mail, PIM and other Data services have to offer their business.
If 15 minutes is of a concern they should have a much greater appreciation of what a BES can do for them.
Cheap and nasty can be done with active sync and a mobile phone.
BlackBerry is for real performers!