FenixEdu has been in use for the last 10 years, and in continuous development over that time, so I would say it its mature.

It didn't started as a LMS, actually started as a Academic Management System. We needed a system to control all the academic administrative operations. Later we developed the LMS system connected with the AMS.

Right now we are on the process of replacing our old LMS with a new one. We have very cool ideas that we are developing right now (timeline based view for the students, tools for interactive presentations, transparent support for MOOCs, etc.)