Here's a copy of my BootCTR9, CBM9, Corbenik, Arm9Select, and Luma3DS boot configurations if anyone would like to try them. They are configured to run Luma by default, but they also run every A9LH CFW and app out there (except BootAnim9, but feel free to add it if you prefer eyecandy over speed, it shouldn't break anything, except maybe the Luma one). Alternate configuration files are included so you can make any of the primary CFWs the default.
BootCTR9 runs GW on B, Luma on A, ReiNAND on X, Cakes on Y, Corbenik on start, Decrypt9 on up, Godmode9 on down, EmuNAND9 on left, and CBM9 on right for loading everything else (has "Apps" and "CFWs" pseudo folders to keep things from getting congested). Whatever you choose for the default, it's key will be undefined, as there is no need -- pressing an undefined key loads the default.
CBM9 runs Luma by default (or luma if you switched .ini files). The menu is on down by default. Feel free to change it (IIRC you can do so in menu). I think down works the best though, considering the menu has the default at the top. Also, "Back To Main" doesn't load the exact same initial menu (it's to avoid auto-booting the default when you go back). The default will be missing from the menu when you use "Back To Main" (it's still listed in the CFWs menu though). Truth be told, I'd like to hide the default, so it just shows "CFWs" and "Apps" when you bring up the menu, if there was a way.
Arm9Select is arranged identically to BootCTR9. If you want something other than Luma as a default, rename "default.bin" to "a.bin" and rename something else to default.bin (b.bin for Gateway, or start.bin for Corbenik, for example).
Luma3DS uses the same hotkeys as BootCTR9, but I couldn't put Gateway on B, so I put it on "L+R" instead.
Corbenik: It has a "Chainload" option on its menu (if you set it to auto-boot, you'll need to hold R to bring it up). the CFWs will be listed first, because of the folder structure. You could add more folders ("0" through "5" for example) in each, and move the CFWs and apps into them individually if you don't like alphabetical order, and want to place them in order of preference or something.
I've included screen init payload files. Safe A9lh Installer is in on the CBM9 "Apps" menu in every boot manager except Corbenik, where its on the "Chainload" menu. If you're running v2, find the iso site version of this. I don't consider it safe distributing the version of Safe A9LH installer that makes it possible to downgrade here, since I cant include all files needed, and you will brick if you mix files from different versions.
I've included alternate "boot_config_gw.ini", "boot_config_cakes.ini", "boot_config_corby.ini" and "boot_config_rei.ini" for BootCTR9 so you can choose any default CFW. Just rename "boot_config.ini" to something like "boot_config_luma.ini" and rename "boot_config_gw.ini" to "boot_config.ini" if you want Gateway for default, for example. The same is true for CBM9. Just rename "a9lh.cfg" to "a9lh_luma.cfg" then rename "a9lh_gw.cfg" to "a9lh.cfg" if you want Gateway for default, for example.
Backup your card's current "a9lh" folder and "arm9loaderhax.bin" files before trying mine of course. This is just how I do it. It may not be what's right for everyone. All of the configuration files are in plain text, so feel free to modify it to your tastes. Have fun.
Most Recent Edits: Added Corbenik (6/8/2016). Updated D9, E9, G9 (6/9/2016). Fixed A9LH payloads (I somehow left "no init" payloads in the archive instead of replacing them with "screen init" as I had intended). Fixed CBM9 black screen issues with A9LH v2 and hopefully "no init" as well (6/11/2016). Complete overhaul (6/30/2016).