You guys are overthinking (and confusing tegra fuses with the gamecart controller fuses, they are separate) the whole gamecard update thing.
The reason "Stock_Dangerous" is dangerous in that it will update your gamecart controller to 4.0.0 if it isnt yet, and there's no going back from that. There's no way to burn anti-downgrade fuses once hekate is loaded, since the first thing it does is disable fuse writes (so does fusee, so does SXOS since 1.1, etc).
If you wish to play your cartridges on 4.0.0+ all you have to do is get rid of kip1patch=nogc in your hekate ini (most of you will be using some sort of CFW pack that wont have it anyway, afterwards, which means that you only have to be careful if you DONT want the gc controller to get updated), which will update it.
Also Milenko, please stop saying that "it doesnt matter that you cant use gamecarts on 3.0.x because you have SXOS", the only reason you would want to use gamecarts on older firmwares is if there's a game (on a gamecart) exploit that can be used later on, for which you obviously need the gamecart working WITHOUT AN ALTERNATIVE BOOTLOADER, otherwise running older firmwares doesn't really make sense.