Change a theme to remove menuhax first, then following this guide: http://3ds.guide/. This setting is mostly safe from removed by Nintendo. The problem is, this setting require user to hack into 3DS System files. So it has a small risk of brick. But, if you're understand and following every step of the guide I gave you correctly. Even though you bricked, it can still be fix by hardmod.
Since 11.3 right now is totally unhackable with NFIRM patch. I still stand on suggesting him to go A9LH.If you update on your emuNAND, there shouldn't be any problems and won't lose access. If you want to keep your sysNAND at a lower firmware version, then there's no need to install A9LH unless you want to use functions that require the use of A9LH (such as dumping Sector 0x96 with Decrypt9). But if you want to update your sysNAND, then you'll need to install A9LH first.
I can confirm that I can run 11.3 using MenuHax just fine using emuNAND function on Luma3DS. Just as long as the sysNAND isn't updated.Since 11.3 right now is totally unhackable with NFIRM patch. I still stand on suggesting him to go A9LH.
Better safe than sorry. Well, it's still his choice to move or not.
I know that, I mean. if you or OP accidently update sysNAND, you're doom.I can confirm that I can run 11.3 using MenuHax just fine using emuNAND function on Luma3DS. Just as long as the sysNAND isn't updated.
With the current version of Luma3DS, I think the files on your SD won't change much.I'll se if I can get A9LH working, it will just give me some work because I have a lot of files and folders on my SD card and I don't know what they do, what are required and those who aren't to change from this to A9LH.
OK, after you uninstall menuhax and finish A9LH, this hax folder won't be any of use anymore.
Hold ing select while booting should show Luma3DS version.I don't know how to check the Luma verion :S