Wow, this is exactly what I'm thinking of doing.
I just replaced my old 7100t with an 8830 (really like the 8830 btw) and my 7100t is cut-off from T-Mobile voice and data service and our BES is sending my Exchange data to the 8830. The phone is quite a few months older than it's T-Mobile contract.
I was thinking of wiping all the old user data (which it will probably do soon on it's own because it can't talk to BES), uploading a new policy.bin file and replacing the SIM with a SIM from my personal regular T-Mobile phone. If I do that, will I have full control of the phone? For instance, will that prevent it from getting tangled up with future pushes of IT policies that might re-wipe the new data and keep the BES admin from seeing my personal SMS messages and phone calls?
Lastly, once that is done will I be able to configure all the security policies? I'd still like to set stuff like the data self-destruct after too many failed logins, when the battery is too low, etc.
TIA!
P.S. On the other hand, now that I've seen how much better the 8830 is I'm also thinking it might be better to get a newer BB like a Pearl (just to get the camera and much better LCD). T-Mobile.com says the retail price is $300 and amazon.com says the retail price of a T-Mobile Pearl is $350. $300 is okay with me because that is the same price as a Palm TX for instance. The issue being where the heck do I buy a T-Mobile Pearl sans plan? Is that even possible (the other T-Mobile phone is a To-Go phone and I want to continue to use the To-Go plan so I can't simply upgrade hardware... or can I?)? I've seen a few places that sell unlocked Pearls but I'd like to do everything on the up-and-up, and I get the impression unlocked phones are little iffy (or is that not true?).
P.S. Here is an unlocked 8100 (but it's "reconditioned"):
Overstock.com