As a Logic Pro X user, is using the Onyx utility advisable?

Hello, I am about to erase and reinstall my Mac Pro's boot drive, and will also erase and restore files to one of my two internal hard drives (the one where I keep my Logic Projects and some other files). My other internal HD contains samples, and the structure of it has not changed that much, so I don't plan to erase it.

After this process, I want to maintain the hard drives well after reformatting/reinstalling/restoring files, and I'm wondering if using a utility such as Onyx is a good idea for the boot drive, or unnecessary. I'm also wondering if any kind of regular defragging on the Logic Project drive is a good idea. Any thoughts?

Thanks.

P.S. Just to give a bit more background: I've owned this computer for 4+ years and have never erased it since buying. I've been experiencing a bit of bugginess with Logic (e.g., several "Deep Architecture - please unpack some folders" error messages, even though I don't use folders in my projects, or Midi Timeout errors, when I only have one MIDI driver installed (for an Access Virus TI). So for these and other reasons, I feel it might be a good idea to do the erase/reinstall. Regarding the internal hard drive with Logic Projects, my thinking is that, by erasing and dragging the folders/files back, I can effectively defrag the drive.