OP said wind roms and tmobile roms are interchangeable just don't flash the modems but its ok to flash roms well guess what, if i were you I WOULD NOT even flash interchangeable roms until I'm certain that the OP of a rom thread clearly states they are compatible, for example in the case of the Illusion rom that worked for both Tmobile and ATT and OP said rom is both compatible with either tmobile or att.
When people make custom roms they can add their own custom modem so unless you know for sure that the rom they cooked up doesn't have an incompatible modem then don't flash it.
Remember always becareful and double check. If you root and brick yourself, ODIN RETURN TO STOCK then.
Introducing laser cut apple iCar.