(...) I have the unlimited package plan with Softbank at the moment and I use over 40,000 yen in internet data a month, that that pales in comparison to the 300,000 yen a month setting.
I have been hesitant on buying a n900 because of Softbank's strict rules. I've had a friend before that has had callerID and SMS problems with an older unlocked Nokia on Softbank's service.
I'll think on it more before making a plunge. It sounds like you have to be very careful when using an unlocked phone on their services. That's very aggravating.