So wait...
What I've got from this thread is this:
1. If you can only install BootMii to run from an IOS....
2. You can still use it as a backup restore option for you wii as long as it's not bricked? Yes and in case the system files are not fucked up by the brick and you can access HBC via Preloader you´re fine when its bricked too.
i.e. I have 3.2 and take a nand backup (not as Boot2) then installed 4.1 and take another NAND backup (once I re-hack of course), then I could then replace the new NAND backup (4.1) with the 3.2 ver on the SD card and get back 3.2 by restoring using this IOS installed version? Yes, you can do so if you want.
If yes, then that's still cool and the only risk you'll have is a power out during the restore? Yes.
Nice quick way to jump between wii firmware versions IMO You should only use the restore option if you absolutely must, playing around with it is not good...
That sounds ok to me, let's face it guys, if when installing most other hacks out there the power does do out we'd be bricked anyway. Oh well, yes...