WiiCrazy said:
Patching an unused ios and especially non system menu ios is not a risk I think or is it?
On newer systems only downgrading back to 3.2 and so on causes a risk I guess since old ios is not compatible with new boot2 versions. (because of the timing issue bushing mentioned in his blog post.)
Touching the NAND at all is a risk. Overwriting anything from ninty is a higher risk.
It's best to be as clean as possible when it comes to the NAND, specially on non-vuln-boot1 devices, as recovery might be impossible without ripping the wii open, soldering stuff and using a NAND flasher when the convenient bootmii on boot2 is not available.