I don't have a NAND backup, but then I know exactly what I'm doing. I'd rather not lug around a massive 32 GB backup when I can't restore it myself anyways without paying a fortune to get it hard modded. I'd take the risks, even though there aren't many. I find CBHC to be the most easy install and forget solution. It only has four rules, all of which I'd never do even without CBHC so none apply to me. And with parental controls, guests can't do anything rash either. I truly understand the risks.
I don't think it's absolutely necessary for a backup if the user doesn't have a big enough SD card or is willing enough to spend so much to get it fixed. Bottom line is both the 3DS and the Wiiu are really difficult to ever brick, especially for a long time user. If you brick on wiiu, you always deserve it since it's not an accident but rather a lack of understanding and should have read more info. Outside of CBHC, no chance to brick and don't mention Ftpiiu Everywhere being a threatening tool. That would be like deleting system32 on Windows type of stupidity. This is all just my opinion on how I feel about CBHC and Wiiu NAND backups. Sorry for the rant.
Also it's possible to fix a situation where the gamepad is desynced if you use the sync button to boot up cbhc's menu on startup then boot up an app that sends you to the home menu where you can then fix any syncing issues. Brick by a lack of a gamepad sync would be an awful idea but that can never be the case since there's a way out of it.