Interesting... the 0xFFFF method appears to work OK for me during backup, but when I try to restore it to another N810, even one that's been freshly flashed with Nokia's own image, it complains about checksum errors in rootfs.jffs2 and secondary.bin (these errors seem to be near the start of each file), and fails. That's true whether I try to restore via flasher or 0xFFFF on the PC, piece by piece or all together. This is repeatable, unfortunately. I can backup, but not restore...

I have CSSU and Diablo Turbo installed. Don't know if this affects anything when making the image with 0xFFFF.static?