If you came here, you're probably wondering why you should switch to Arm9LoaderHax (A9LH).
Well, my friend, your answers are going to be slapped on your face. That slap will be full of good ol' knowledge. Now let's begin.
A9LH is an exploit you can install, using a simple guide that I will link
here. It allows one to boot a custom firmware easily (within milliseconds after boot) and give near full control over the system.
A couple custom firmwares that can be booted through this hack is Luma3DS by Aurora Wright, SaltFW by Shadowhand, and ShadowNAND, also by Shadowhand.
Each CFW has it's own separate pros/cons, but a guide can be found
here so you can figure out which one is best for you.
If you own a Gateway, you might look into installing Gateway's version of A9LH. It isn't better than the community's A9LH under any circumstance. Here's why...
The community's A9LH is superior to Gateway's A9LH in many ways.
Like, for one, the community's A9LH has a lot more support and updates than Gateway's. Meaning that your 3DS is a whole lot safer with the community's A9LH than Gateway's. Also, we can boot Gateway's payloads, but Gateway can't boot ours. This gives the community's A9LH an advantage over Gateway's.
Another reason is that if you lose your Gateway card with Gateway's A9LH installed, your kinda screwed. It won't let you boot into Gateway Mode. With the community's A9LH, all you have to do is install it, then you are done. No extra setup required.
Another reason that the community's A9LH is better, is that you can boot most flashcarts in some way. This includes forwarders or just plain old patches. Gateway's A9LH only allows you to use your Gateway card. Only those. And if you use a DSTwo Plus, Gateway will brick your console. And it can't be recovered through a normal hardmod, it can only be recovered through a Raspberry Pi.
And another reason is that Gateway's A9LH is worse, is that
YOU CAN'T UPDATE! When you update, you lose A9LH completely! This also means that you won't be able to play the latest games that require a higher version than what you have. With the community's A9LH, you can use a CFW with FIRM protection, like Luma3DS, and update normally, and you won't have to worry about losing A9LH.
Again, do not install Gateway's A9LH! Just don't!
MenuHax
If you are a current Emunand user, you might have an exploit called MenuHax installed. Although it is a slightly effective way to boot Emunand, A9LH is way better. A few reasons are...
A9LH has a 100% boot rate! Meaning no more rebooting to just get an exploit to work.
A9LH is much faster than MenuHax, a comparison can be found
here.
Also, MenuHax can be lost through a system update, and if the exploit that it relies on is patched, you can't install it again until another exploit is found that can boot it.
By now, you probably know the benefits of A9LH, but you are still scared to install it. This leads me to...
How safe the guide is!
Over the months, the guide has become a whole lot safer! The brick rate has been reduced and the guide has become a lot shorter.
At one point, you had to downgrade using a homebrew app. Now, people use a ctrtransfer to downgrade, a more stable method.
OTPLess A9LH installations are now available for the New 3DS, allowing users to completely skip a part of the guide.
The guide can be done within a time span of about an hour and a half. A time span that most people have.
The guide is also still being updated with the safest and latest methods of installing A9LH! This includes the newest method, waithax. This little exploit allows you to downgrade from the 11.0 and 11.1 NATIVE_FIRM to a 10.4 one. This can be then downgraded to 9.2 with regular exploits, allowing you to install A9LH properly!
Now that is A9LH for ya! I hope I have persuaded you into wanting to install this amazing exploit!
If I have some inaccurate info/typos, please tell me what it is and the correct info so I can fix it. Also tell me if I leave out some stuff. Thanks!