As far as the constant switching, All of the phones have been unlocked and used on T-mobile, except the iPhone 3g I had, I actually carried two carriers for awhile. I decided to pay the ETF on T-mobile and ATT inorder to get the Storm, and can comfortably say that I am glad I did.
I can honestly say that the Storm is the best so far, the only thing the iPhone had on my Storm, was the ease of media loading, and the browser in my opinion was easier to use. I think the only thing I will miss from all of my phones is the G1, and its barcode scanner, and the unlimited tethering...