For me, Plex is/was only for video. Plex was a fork of XBMC/KODI and therefore made mostly for video 'n stuff. It is, same with Kodi, a bad idea to pump more than 500 songs into the database. The software just can handle that, so it always a good idea to look out for software, which tries to specialize, like Madsonic (although, I got a bit worried, when Madevil tried to make it a state-of-the-art-videoplayer too, but hopefully, that never will continue and only rudimental videoplaying is available.)
The Plex-Team made a really great job designing their UI, having stable Server and Client software and going to the market (with their paid subscriptions).
Its somehow like Madsonic subscriptions, you can use mostly for free (as in no money), but for the good luxury you have to pay. Thats ok by me, we all need some bread and want to pay the rent. Keep in mind, that a steady team needs a steady income ;-) Unfortunately, we're not in 1990 anymore, where ppl. coded for fun and fame! (those ppl. are now old and employed and don't have much sparetime anymore. Some of them have a wife and children too, call it a family, or just Real Life. Thats very unfortunat for a coders life...)
IF this is a one man show, it is a big success and a very impressive and applaudably piece of software it is too! (I guess, Madevil has a Designer and a Webhoster in his crew. If you code this software *and* do the Graphics *and* texting *and* translations *and* hosting *and* billing and all the things I forget, then you are an unbelivable one man show)
Anyways, a (hopefully decent) Mobile App for IOS is something, I'm missing too, but atm I'm more concerned that all the bugs are fixed :-)
Of course, Madsonic works great -out of the box- but when you go in detail...well, it lacks some of the
heavily development.