I said nothing about replacing the mii channel. I said you didn't have to use save manager gx for the majority of these saves, especially when you have to have made a save for each of these games to begin with. the official method is much faster and convenient.
Not really, you still need to create a new save file for each game before those saves can even show up in the SD menu, then you need to delete each save individually from the NAND first then copy them one by one from the SD menu and even then most games won’t work because Nintendo put a copy protection for every game that has access to the internet even if only to view high scores.
Wii Save Manager let’s you copy all of your saves and bypass the copy protection with one single step, only downside is you still need to create a new save file for each game first but at least you don’t need to delete each individual one first to copy over it nor do you have to do it for each game separately but instead copy all at once.
Edit: and if you rather use EmuNAND you don’t even need to do any of that, just use your Wii EmuNAND to the vWii and it shall still load all of your save data and I believe your Miis as well.