Yep, I'm in the exact same boat as you Freak... xBackup seems like a waste of money now. And like you say it will happen all over again with 6.x.Thankfully this is happening while 501 is still being signed... phew!
This is my second time restoring to factory. First was when the CLI jailbreak went bad. Now xBackup restore... This time I'm gonna go real slow like and do everything manually.
Do you know of any way to find out what packages / tweaks etc you have paid for / had installed? i.e. I want a list that I can go through 1 by 1 and check before I install.