Your signature says the only dumb question is the one that's not asked.
Why do I need a NAND backup? I always keep a copy of my current ROM, and the last stable one I've used on my sd card. I also use Titanium for all my apps and setting. If I understand correctly NAND backs up the ROM, but it I have the file I can just do a clean install, right? If this is not correct, please correct me. If it is, then what benefits are there doing the NAND restore over doing a reinstall?