What do you see as music vs. HT split ? If lots of music, what kind of music and how loud ?

The main advantages of the 50 over the GM here will be (a) ability to play louder, (b) ability to play music without a sub.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8