can anyone tell me why

[mrmet044]

i presently have the touch pro with full internet, text messaging, email, and picture mail plan. i was thinking about getting the blackberry tour and sprint told me the plan i have is no good and i would have to pay an additional $30 each month for a blackberry plan. when i ask why, no one seems to be able to give me an answer except for saying its a software issue. if i have a data plan for one phone why wouldnt it be good for other phones. does anyone know what this is all about. thanks in advance