The NAND and console IDs are stored in the encrypted NAND. A NAND image does only work on the 3DS, on that it was made. Each 3DS uses his own keys for NAND en-/decryption. So no NAND sharing. Only up- and dowgrading currently.
But be aware. The 3DS deletes all contents on the SD card with missing tickets in the NAND. Downloading a new game on the latest firmware and dowgrading results in the 3DS deletes it!Looks like nintendo patched physical nand swapping through hardware flashing
What? is this something new?
This happened before but only after cloning stuff abusing of the system transfer.
Also, I recall people saying that games are still stored on the SD card, even after the tickets for them get delete
This is what I'm understanding from your info: If games that were never obtained through an old NAND backup are bought/downloaded on emuNAND/current NAND, after using this old NAND backup again the system will be missing the new content that never was obtained here. After flashing back/booting emuNAND, the games will be deleted on the newer NAND backup as well? Or you meant something different?