Still very happily running Mohave here. I heard too many people describe Catalina as “Apple’s Vista” etc, but even so did try installing it at around the .2 revision. Even then it lost about 60% of my obsessively curated album cover art for no apparent reason, so I reversed out to a backup (thankfully I have a couple of 1TB SSDs and use CCC, so I just swapped the physical drive out!). I’m not going near it again unless anyone gives me damn good reason too. Mohave seems totally stable and does everything I need. I suspect I’ll retire the MacBook on it (its a maxed-out mid-2012 i7 13”).
To be honest, since acting as a music server isn't particularly demanding of any Mac built in the last decade or so, there's not much reason to upgrade the OS. Golden rule, 'if it ain't broke, don't fix it...'
If you do feel the compulsion to upgrade at any point, it's always best to check first if any third-party software vendor, eg. Audirvana, has a build compatible with your target OS.
To be fair I have a 2012 Mac mini music server with SSD and 8GB of RAM which I can boot from High Sierra or Catalina, either runs Audirvana without issue. In truth, without checking, I can't remember which version's currently running the show, but that perhaps is more indicative of how unimportant file-based replay has become around these parts than anything else.
No way I would let Catalina near the production Mac in the office. I did have Mojave running on that (two versions, each on its own partition) for a while, but dumped it after a few weeks of experimenting. IME High Sierra is rock solid, everything since is not.
The underlying fundamental problem I think is the self-inflicted stupidity of an annual update. That was fair enough in the early days of OS X when change and progress were rapid, but latterly it's a nonsense. Every new version of OS brings an increasing number of developer builds which are often pretty rough round the edges until very late in the day and ever-increasing UI inconsistencies/glitches/f***-ups.
The glimmer of hope is that having inflicted the flakey iOS12 on the world, they turned that around with iOS13, which 'under the bonnet,' I understand, is a lot better than its predecessor.
Let's hope they manage the same turnaround with Big Sur.
