I listen to the music and the movies about equally.
I have a very good main system, with 7.1 speakers. It is optimised for music, including surround music. Consequently it is very good for 2 channel music as well. The rear speakers are not in the best 7.1 movie surround position (they are all floorstanders, including center speaker) but still do a great job with movies. I agree that a good system can reproduce both music and movies well. I suspect a system optimised for music copes with movies very well too. A system optimised for movies may make compromises that affect music, particularly in terms of bass reproduction and multichannel playback (too difused sounds from the rear speakers).
Danijel