Stay on 10.1 for the moment, as it is the
latest version that is theoretically possible to use snshax on. I suggest not using this as an excuse for not updating at the moment, because its all PoC and people on this forum is hyping out of nothing.
Luckily, smealum released some new free ways to get homebrew this Christmas. First of all you need the
newest homebrew starter kit.
After you extracted it to the root of your SD card (manually or using the tool in settings), you can go to the
browserhax page on the 3ds. This, if you did this correctly, put you into the homebrew launcher.
There is quite a few ways to go about this, but to get a permanent way to get userland homebrew, even when updating, is ironfall. Smealum and his team released a new way (and yet patched) to download older versions of eshop titles.
1. Use the shortcut called "eShop - old version downloader" in the launcher, and it should put you in the supposedly normal eshop.
2. Search for ironfall, and download it.
3. Open it at least once, but don't play or create any saves.
4. Go back to homebrew using browserhax (or menuhax if you decide to install it before ironhax) and run the ironhax installer.
5. You now (should) have a permanent way to access userland homebrew!
If you want a less-permanent, more convenient, way to access homebrew, you should look at menuhax. Menuhax is allows you to access the homebrew launcher before even going into the home menu, and it can be installed using the installer included in the starter kit. The default button to activate is L, however it can be changed, and even set to autoboot!
Hope this helps, and enjoy playing with emulators on the N3DS.
Edit before posting:
You might want to install a later version of ironfall, that one sounds bugged. I think you can just delete the save.
I also suggest looking into retroarch for 3ds, which is what I use and I have no problems for my N3ds. They have emulators for every console pre-N64 you can think of, and they run all at near/full-speed.