Yeah, true, thanks for pointing that out. That's another drawback I hadn't thought about.Unlocking bootloader will erase device.
But at least I would have a working nandroid backup of stock B303 that I could restore in case the rollback bricks my tab.
By the way, would that also be an option to go to official B307: If someone with stock B307 made and shared a nandroid backup?
I hate it that I have to invest so much time into just updating my stock tablet. For everybody else who got B303 through FirmwareFinder, the B307 update just worked? Why doesn't it for me?