Well I have no personal experience, but from what I have extensively read, you certainly can unlock it using older firmware, and you *don't* have to upgrade to the new firmware. You can happily keep it on the old one. There's a new jailbreak out for the new firmware now anyhow. And Apple are going to make the unlocked French Iphone only display a french language OS. Basically if you actually want all the usuability and enjoyment out of one with having to worry about not constantly blocking firmware, repatching it all the time and other wretched tasks, just buy one from O2!
S.