December 8th, 2012, 10:16 am
I just got myself a shiny new Wii U and wanted to transfer my stuff over from my Wii. Here's what happens when you do this, and how I attempted to avoid issues with having a modded Wii.
First, and most importantly, use BootMii to make a backup of your Wii as the transfer process will delete all transferred data from your Wii...channels, saves, Miis, etc.
Second, I went through and removed all illegitimate software and related saves (HBC, WiiMC Channel, etc) from the system. Everything is going to get rewritten anyway, so better safe than sorry. I also turned off all Priiloader hacks to avoid complications. I left save data alone as it's just inert data that won't mess with anything and shouldn't be a problem.
The transfer process will not move Wii Channels (Netflix, Hulu, YouTube, Nintendo Channel, etc). It will also not move certain save data (it states this in the Transfer instructions)...here's what save data wasn't moved on my system:
Miis stored in the Mii Parade will not be transferred.
fluidity, Jett Rocket, Excitebike (WiiWare), You, Me & the Cubes, The Magic Oblesk, NyxQuest, Cave Story, And Yet It Moves, Sonic (WiiWare), FAST Racing League
Now, these are all titles that were not installed in the System Memory, so this may be why the save data wasn't transferred. These are also titles that were not purchased through the Shop Channel and therefore are not in my account history (I know, shame on me, but I have also purchased just as many titles, so I'm not all bad) so this may also be why they weren't transferred.
It's tempting to move a couple of these back into the system memory and see if they will transfer, despite not be valid purchases.
Any games you have that get online updates (Call of Duty) and have outstanding updates will be updated as part of the transfer process.
Anyway, as it stands, the transfer was successful through this method, and restoring the NAND backup will restore everything back to the Wii as though nothing happened.