I think you have done a really good job of setting up your algorithms for unison and solo vocal sight reading. That being said, sometimes the ranges of the melodies frequently extend beyond what some of our younger musicians can perform successfully.
I propose that we either have access to the ability to define a range for an instrument or voice in the assignment set up, or that we be allowed to tweak standard levels in the system in the "custom level" set up screen (ex. use the pitch and rhythmic parameters of Level II but limit or widen the ranges of pitches possible for a given instrument/voice).
I LOVE this idea!