For an extra $50, I'd rather just have 3G hardware even if I don't renew access fees every month, or even rarely at all depending on what the network services and apps offer.
What I don't want to do is end up buying a second PSV when opting to "save" $50 with a WiFi only model in the event that the device is good enough to actually use regularly as a net enabled portable.
I'm assuming the non-contract monthly fee will be the same as the AT&T iPad at $20, which is reasonable.
Not worried about data limitations since I'm already a 3G AT&T user and it's never been an issue and I have no intention of suddenly downloading GBs of data through 3G any time soon.