Backstory; (skip down to Short questions, if you want)
I'm a former Treo owner who switched to the iPhone. Love it, actually, except for one thing: it's not officially unlockable. I've been able to get the unlock codes for years now from AT&T, and able to travel internationally with other SIMs, etc. As an Apple fan, I'm a little disappointed in the email client (though I know that will change with 2.0), and the lack of AIM, or any other chat application for that matter. My Treo is fat and ugly (both inside and out).

My corporation has a BB server, and I'm not terribly familiar with the platform (do you setup personal emails that are forwarded to R.I.M.?) but I understand the push email is great. I won't be using it for work, though. Also, I have a FAN, so those prices apply (yay).

I really don't want to wait for the 9900 series, since it's still in rumorland, and will probably not be very price-competitive to the 83xx series, as tempting as it might be. I will be using it for more travel lately (some work, mostly not; I'll use my laptop for that), and would like to use its GPS features. I understand that TeleNav is a great feature, albeit a paid-for option.

Short questions
a) My understanding is that the iPhone SIM will work and the two drawbacks are 1) Visual Voicemail becomes annoying with text alerts on the Curve, and 2) if you don't have a BB plan enabled, you will not get push email?

b) AIM application uses the data stream correct? And there is an application available? Google returns older threads about an AIM client not existing, and not working on AT&T; these are outdated, correct?

Any further thoughts, experiences ("wait a few more weeks", "don't switch"), etc. appreciated. Thanks a million.