Last year I went through an expensive round with Apple Match (gave it to myself for my birthday, yet!), which resulted in the loss of all my non-Apple purchases except for my secret copy on a Snow Leopard laptop. Cutting to the chase, I've successfully moved all 1843 cuts to a new AirBook, but I'm in fear that I'll accidentally open iTunes while I have the internet connected, thus allowing iCloud to slip in and steal them again, in the guise of keeping everything safe and sound in the cloud.
What I'd like to do is merge these 1843 with my $10/month purchases from the store, and quick hide everything in a closet or something.
Meanwhile, I'm off to upgrade a Mini to Sierra. Using a t-mobile hotspot, I hope.
Sasha, although I use Apple Music (and love it) I've never used Apple Match, so haven't had any experiences with losing music. However, there are plenty of other people complaining about it - here's just one blog post and lots of comments:
http://www.imore.com/no-apple-music-not-de...ess-you-tell-itI suspect that in a lot of instances, it's a case of using automatic synching and not understanding what is happening. (synching from the phone to the main library for instance, and ending up with the phone's much smaller library on the computer perhaps). Whether things are actually being deleted mysteriously and without any rational explanation is not really clear. It does appear that this has happened to a few, however.
As for you - first off - do you have a current backup of the new Airbook AND all a backup of your "secret copy" on the older laptop. (Two separate backups)? You should. Hard drives are cheap - replacing music or files is not. Make sure you have current backups - and I recommend either SuperDuper or Carbon Copy Cloner for this - they give you BOOTABLE backups, which Time Machine does not.
Once you have good, working backups (please test them - boot from the external drives) then you should be good to go with turning on Apple Match again. I'd just be very careful about synching anything. I never allow any automatic synching - mostly because my main music library is way too big for any synching with a phone, iPad or even my laptop. My laptop has a rather peculiar selection of music in the iTunes library - it's a decidedly oddball subset of the main library and I really don't remember how it got to be the way it is, but it doesn't matter really, as I usually just stream Apple Music from it to our Sonos speakers and so it doesn't much matter what I have locally.
Good luck - and let us know how it goes.