Thank you!
Okay so, from what I understand, being in emuNand is actually just being in Gateway mode? Are these the same thing? Maybe I just haven't gotten that far yet.
Edit: And if anyone is willing, can you explain what sysNAND and emuNAND being linked or unlinked means?
Gateway Mode is like a wrapper around the system that does things like disable signature checks, add a hook for the game menu, and so on.
emuNand is a separate instance of your internal memory stored on the SD card, allowing you to install things to it that you can't or won't install to your main system memory (such as updates that would leave your main system non-exploitable). Most of the time, you will likely be running emuNand in Gateway Mode. If you want to run a retail card, you will likely use emuNand in Classic Mode. If you want to mess with your sysNand for some reason (such as to install certain versions of System Software), you will boot sysNand in Gateway Mode to run your CIA installer. If you want to run DS games, or an unmodified system for some reason, you can do that when you first boot the system in sysNand without Gateway Mode.
The 3DS contains a unique ID that it uses for various things, such as storing files on your SD card. When you first create an emuNand, it is an exact copy of your sysNand, and that means using the same unique ID. Because of this, the two nands will use the same folder, and see each others' files. This is what it means to be "linked", since changes to one can often cause changes to the other. This is usually more hassle than it's worth, so most users choose to unlink them by formatting one of the two nands. This causes the formatted one to choose a new unique ID, and thus use a different folder, and the two no longer step on each others' toes.
Also, I heard I can't use my saves for games I've already started. That's a bit of a downer. :/ If anyone can dispel this, that'd be grand, but it's all good.
If you are using an Old 3DS and downgrade your System Version to 4.x, it breaks the encryption used in some retail games. You will lose the saves of any retail game using the encryption introduced in 6.x. Also, if you start a game, and then change the header to go online, I believe that also breaks the encryption key used for the save, but I haven't experimented with that.
It is incredibly easy to dump your own cartridge. Launch the gateway exploit with the red card not inserted, so the menu comes up. Pick the option to dump a cartridge. Put cartridge in and press A. Come back in an hour or so depending how big the game file is. It will be saved in the 3DS' SD card.
Minor point, you can also hold L while starting the launcher to enter the menu, without having to remove the card. In this case, since the card will need to be removed to insert the card to dump, it doesn't make much difference, but it could be helpful to know.
I think I'm gonna' just go with .3dz and hope Nintendo doesn't get mad at me for using the same header across a million games.
I want to have a great rescue team, after all snarfle snarf.
So far, there have been no reports of bans from using the same private header with multiple games. Just as long as the Card ID is not online twice at the same time, you're fine. I personally use one header for all my games, and have yet to be banned.