I would love the option to store Emby's database in MySQL - I have a setup that serves around 30 people and I feel that there would be real performance gains by using a proper relational backend over SQLite (I'm presuming).
On top of this it would make life easier for me when reporting on watched status a cross users.
Yes but that makes another assumption - not just the support of MySql but the support of all the components of our server for simultaneous access to the database by other servers. That may be implied in your mind but it is an entirely different request (and yet another layer of complexity).