I'm thinking how nice it would be to have a split view, or two parallel galley views of the same piece so that things can be compared or copy and pasted from measures 41-49 to measures 134-142. Music is very pattern based, and repetition based. Working on more than one point in the score at the same time would be very beneficial.

Another feature I'd give most anything for would be direct native Roman Numeral figured bass notation (I'd be happy to enter it myself (automatic would be insane).).