The title pretty much says it all. My wife and I are big fans of T-Mobile (and $6/month T-MobileWeb) and hate AT&T, but getting an AT&T family plan is a way for us to get a subsidized-price 3GS ... I gave her my original iPhone and got a 3GS for $200, we are in our 30 day trial period, and the 3G speed is nice, but as my wife says, we're already in front of our computers all day with wired ethernet and Wi-fi; it's not as if we travel that much. The AT&T family plan with EDGE and 3G data costs us about $35/month more than T-Mobile, which isn't pocket change over the life of a 2 year contract. My alternative is to buy someone's officially unlocked 3G on Craig's List for $350 (the 3GS is too expensive at over $500) and go back to T-Mobile.

Can anyone weigh in here?

I love t-mobile. In the end, I decided that staying with a good cell provider was more important than having an iPhone. It's not as sleek and doesn't have a lot of the cool apps, but I can do everything I *have* to do with a PDA with a Palm or Windows Mobile device.

Is there a way to spoof the IMEI so the iPhone doesn't appear like an iPhone on the AT&T network? I know that it's possible to use a different SIM in a different phone and register that, but I was told that AT&T scans the network for iPhones and adds the requisite data plan.