Issue restoring nand backup

I finally made the move towards the Wii U this holiday season. I wanted to transfer our mii's over and discovered we could perform a transfer. I understood that the transfer would delete the mii's and content from the source wii. This was something I didn't want. I performed a nand backup of my wii before running the transfer tool, and hoped to restore that backup after transfering the data to the Wii U.

When I tried to run the nand restore, I was blocked with a message that indicated I didn't have bootmii installed on /boot2 and it was dangerous to proceed. I had bootmii installed on ios. I don't think I could proceed because of the Konami code and my lack of a game cube controller. I installed bootmii on boot2 and tried to restore again. The restore process was happy about the bootmii but complained that the nand backup was for a different wii, and is asking for the Konami code again.

At this point I'm uncertain if it's safe to restore from my backup. I don't know a whole lot about bootmii, nand backups, and keys. Would reinstalling bootmii to boot2 change the nand key and cause this type of warning? Is is safe to restore my backup by entering the Konami code?

I've grown a bit attached to my Wii, hence the time it's taken to move to the Wii U. I'd really rather not brick it, and it would be nice to be able to have all the save game and mii content before the transfer tool pillaged it.

Don't. That's a really risky move. I'm assuming that the transfer tool has reset your wii or something, causing your keys to be reset (idk). If that it the case, then you'll screw your wii over by restoring that backup.