I'm certainly not going to recommend you flash any CFW to it yet. It's an older model and we dont know what type of nand flash it has. To convert it to a retail unit is simple. Just update to the latest firmware (3.55). It's probably safe to update through the XMB from online update or put the update on a flash drive and follow instructions on how to do that.
It's up to you if you feel safe flashing shit from the internet to it. If I was you I would wait just a bit longer to let other people make the mistakes before you. I would also be trying to compare that demo model to regual model and try to tell exactly which one it is so you have an educated guess as to whether the CFW will work on that model or not. You are braving dangerous territory but I think you will be fine