How to do it: I know you have to use OpenFirmInstaller, but idk how that works.
Is it safe: I don't see why it wouldn't be.
Advantages: If you want to press buttons to load other .firm files without using Luma's chainloader, you can do that here. Alternately, if you absolutely hate GodMode9 you can make a NAND backup here.
Disadvantages: You can't dump the bootroms & I don't know how to set up OFI.
tl;dr all it's functionality and more is included with Luma and GodMode9.