I am thinking mainly about solos. Perhaps, some songs could have a separate scoreboard for their more iconic or difficult part, like the solo.

In many cases, high level songs have that level only because of the solo, but the rest is quite easy. So, if you want to have an (in)sane competition with some of your friends you almost need to spend more time trying to get the rest of the easy parts perfect than actually practicing the hard part (and that's a bit of a waste of your practice time, in my opinion).

It would be great also for those songs you are not really into, but which happen to have a great solo in them.