In my own experience, the MAMP folder is not one that can easily be moved around. I am sure that if you have a lot of skills with Apache, etc., you could do it. But not I. On my Mac, when I install MAMP, I let the install do its thing. I don't touch it. Upgrades are always challenging.
For upgrades, I tend to install a new MAMP (by renaming my old), I backup each database and restore it. I can move my various moodles in htdocs, this seems to work. And I also have success moving moodledata folders.
I find that this is a bit of work, and I only do it about once a year or so.
All of this is a good experience, but it is not easy to explain to others. Fortunately, it's only a local install so you don't clobber your production moodle.