Well I have used my phone as modem and downloaded a 10mb application and surfed the internet. I got my first bill from sprint and there are no additional data charges. So don't know what to tell you other then try it. If for some reason they do try and charge you (they won't) then tell them that you spoke with 4 different representatives for Sprint and they assured you that there would be no additional charges....they cant charge you if they told you they wouldn't....
I dont blame you. As previously stated in one of my posts I spent a good hour talking with a bunch of different reps to assure I would not be charged. Dont be surprised when most of the people you end up talking to have no idea what you are talking about. You have to be patient and get someone who knows what you are asking them. I think that the fear about BB data charges date back to the pre-unlimited data plans.....
Hopefully....but yeah I know what you mean, Ive had that happen in the past where I talked to 4 different people from customer service and what there telling me is in fact 100% BS and guesses.