Best current distro for LMS on an RPI4 ?

Short answer: pCP.

Longer answer: certainly depends on your needs. If you really just want
LMS easily installed and running, go for it. If you want to run
additional software on the same Pi, then it's not the first choice.

> Finally, there's pCP. I see that can also run LMS, and whilst the idea
> of running from RAM rather than the SD card is appealing, I wonder how
> well this works with the music library on a slowish old fileserver ? Can

Great! It's what I've been using for 2-3 years. That Pi3B+ is much
faster than LMS on the NAS where I still have the files (ReadyNAS Duo v2).

> you put the database cache local to the Pi, either on the SD card, a USB
> drive, or even cached in RAM (on a 4GB Pi) ? This is for a music
> collection with roughly 15000 tracks.

I'd say pick the simplest setup. Really. I'm using all default settings
for LMS on pCP. Which means that cache etc. is stored on the SD card. I
haven't had a corrupted card in all this time.

> Finally (I promise !) any issues re: CIFS vs NFS for sharing the music
> library with the Pi ?

I'm using NFS now because I can, and I believe it's faster. But I bet
CIFS is being used by many.

--

Michael