Let me drop you a couple of things to consider about leaving your BB.
1. Not sure if Android Exchange integration gives you full access to your Global Address Book. BB and Palm do. Last time I tried Android, it didn't. Not a show stopper for me, because I save all my GAB entries that I really need to my personal address book.
2. Dialing conf calls, or numbers with extensions. BB does it well. for instance, in your BB, if you have a number entry that looks like this: 555-555-5555 x123456789# BB hyperlinks the entire thing. when you dial it, the main number is dialed, then once connected, you get a popup that asks: Dial 123456789# ? All you do is click and you are in your conf call

# is usually what you have to press after entering a conference ID, depending on what con call system you are using. This rocks when on the road and on BT headset. BB and Palm again do this. Palm only recently. Android did not link the whole thing together when I tested it.
3. Email search. UGH! This one was my show stopper, last Android I tried. I have thousands of emails a month and constantly need to sort through them to find something, when out and about. BB does it and now Palm as well.
If you are a heavy BB user and for business, consider these issues before making the jump, unless Android future versions have it solved. I have my fingers crossed! I want an Evo so bad. If anyone here knows if those are fixed now, please do share