Excellent!

Didn't the MPP also allow you to write on the chart with colors to make notes?

On a busy chart, color coding jump points (sometimes, the artist doesn't ALWAYS want to do the structure of the chart) or cue points, skipped sections, things like that are great.

On pro shows, I'll often use a highlighter to quickly guide my eye across a chart to a cue, or emphasize an instruction without obstructing the chart itself. Something along those lines (a light color semi-wide line that doesn't obscure the chart) would be of amazing use...