Hardware thinking about buying a ps3 demo unit

[smash_brew]

So i'm thinking about buying a ps3 demo model from someone that purchased the unit from circuit city when they we're going out of business. It was recently updated to 3.55 in an attempt to get rid of the demo mode by the current owner. this however did not rid the system of demo mode. i have the demo unlock code which takes it out of demo mode but still restricts access to psn, and the code must be entered again every time the unit is powered off. I've read up on a method involving a jailbreak devise and installing cfw which would rid the machine of the demo mode and allow me to connect to psn, as well as not have to enter said code every time i turn it on and essentially turn it into a retail unit. I was wondering if anyone here has any experience with a ps3 demo unit and ridding it of demo mode. I just want to get some insight on the best way to deal with the demo mode issue, whats a fair price for the unit and if anyone knows about backward compatibility and other os with a demo model. if anyone has any insight i would greatly appreciate it. thanks in advance.