connection speed

So I've searched on connection speed here and have not found what I'm looking for. I'm trying to understand if there is a difference in the BB phones related to connection to internet speed. I've got an 8530 and am trying to decide if I want to get a bold 2 or whatever the heck that thing is called. THe person at Sprint told me that BB's connect on their own internet and don't use the Sprint internet network and as such, the different handsets (BB) all connect at the same BB limited speed. She said the 1XEV business does not change per handset. I THOUGHT that there was a REV A speed and a REV O (or something) that were different. Also, where the heck does 3G come in there? According to the Sprint gal, it doesn't make any difference. THat seems strange to me. . . can you guys set it straight for me? Is the processor speed of the phone the only diff re: connection when talking BB?
Thanks,