The Touch Pro does not have any specific plan requirements compared to any other WinMo smartphone. Should work just fineas long as you aleeady have an EVDO device, if you have an older 1xRTT device you will probably have to change the plan since the coding is now expired.
The only way you'd run into a problem is if you went with a Blackberry anytime in the future. Then, we'd have to make some changes since technically that provisions on Blackberry's network, which we don't have direct control over. Any other device, we directly provide the data for.
To Sprint Employee - If I am reading this right the Touch Pro 2 does not require a data plan to activate? I am getting mine in a few days to replace my broken Touch Pro. It will be just an excahnge, no renewal or upgrade.