[exDM69]

No, there are no disadvantages to using the Multiboot protocol, but there are numerous advantages.

The biggest advantage is that your kernel images are a bootable, debuggable ELF binary.

The emphasis being on "debuggable", you can easily plug in GDB to QEMU and use a proper debugger with your bare metal projects. Using GDB is much better than using the built-in debugging facilities of QEMU or Bochs. You can get the source view, set breakpoints and do everything you normally do in a debugger. In QEMU/Bochs built-in debuggers you have no source view and can only inspect memory and registers - not variables with symbolic names.

Here's some examples and documentation on building a debuggable ELF image for bare metal project, which I contributed to someone else's project:

https://github.com/Overv/MineAssemble/commit/56e317a28d069f4...