Thinking of switching from Sprint to Tmobile.. few questions

[Phen0m]

My first question is..How fast is Tmobiles data network? Can it compare to Sprint's(who is pretty fast seemingly).
Also, how is the insurance aspect handled on Tmobile with the unsubsidized phones(Touch HD, Unlocked iphone etc)? With Sprint i can take in my Treo, TP etc into a service center.. if the issue can't be fixed, they will ship me a new one asap.

Also, for those wondering, the reason i'm switching is due to the lack of simultaneous data/phone usage on sprint/CDMA.. this is huge to me as i utilize both constantly. Otherwise Sprint has been perfect!

Thanks for the help!