So to be clear, I'm not fully up to speed after going through the last few pages.
What is important in order to be able to do a region swap is a valid SecureInfo_A from a 3DS (new or old) from the region you want?
So you can swap a US old 3DS with a JPN N3DS, in theory?
Interested in the answer to this. I would like to be able to make an emuNand on my JPN N3ds XL with US region using my O3ds XL's SecureInfo_A. Is it model-specific?