Support of VSTi (VST intruments)
I would like to suggest you to add support for VST instruments, so the playing of the scores become really beautiful. VST instruments are very usable and the quality of the sound would be enough to publish music directly from MuseScore without additional edition.
I hope you consider this, it would save a lot of time, and give a lot of benefits.
There are many open source VST hosts that you can use as base. In example, this little program that is very versatile:
The author has in open source the anterior versions of the program. He says he does not longer put the program in open source because the users of the code never gave them credits. Maybe if you offer him to give him some credit in MuseScore's next version he would realise the source to you. Else you still can use the other code that is still a very usable program that host VST and VSTi .
I hope you can do it. Thank you.