Music lessons add about as much as XP as the long 5 hour missions but you can do 5 missions in the same span of time. So in theory you could get 600 XP versus 136 XP.
So with 3700 XP to get to level 75, in theory, that could be done in about a day and a half but realistically, it will take about two and a half days to get there. A lot faster than with just doing the missions and I suppose that is the trade-off for not earning starbits.
Interestingly, the player rankings has also improved a bit, perhaps because I am playing more often.
Ego has come down a bit and probably by the time I have reached level 75 then it would come down to 0 or maybe close to 0 from the 5 or 6 percent that it is now.