Haha i'm not sure I would have gone to the Apple store with a phone that had been jailbroken, or a mac with the software still on it
I jailbroke my 3G over a year ago and got used to all the extra things you could do, but when I upgraded to os4 it was waaaaaaaay too slow so I went back to standard.
There is some great backup software on cydia that would have sorted out your problem maybe.
If the Apple staff had got funny with me I would have said if they unlocked the potential of their hardware then nobody would need to hack it I had most of the os4 'new updates' on my jailbroken phone months before!
That said I my iPhone, you can stick your crackberries and flangedroids up your bum!