if only devs could confirm that. looks like it's the first and last time i try to help / tell people things on reddit since most of them think we're stupid enough to update from gateway and won't check if we were right.Its sysNAND only. Regardless if you have an old3DS or new3DS, if you launch Gateway's arm9loaderhax payload to boot Gateway CFW 11.3 sysNAND, Nintendo must've added a firm0/firm1 restore function for when you boot your 3DS, so since Gateway doesn't patch that, Nintendo can overwrite it to remove A9LH.
thx for your detailed answer i'm relieved