I just got back from a Virginia/D.C. trip that included judging the two final rounds of the ETW solo competition.
For me, one of the biggest challenges in judging these things is the not-so-simple process of listening attentively while trying to write intelligently. It goes something like this: you listen, you hear something (good or bad) that deserves a written comment. You try to write with decent handwriting, knowing that your comments might impact the person whom you are evaluating. I always want to write something of value to the eventual reader. But, as you write this, the music keeps rolling along and deserves your attention. The challenge is exacerbated when you are dealing with a score you don't know well as was the case with the Schnyder Sonata and the Amis Preludes.
Here's an idea I've thought of but haven't acted on. What if you laid one of those transparency sheets over a copy of the music and wrote comments directly onto the transparency? Then you could quickly refer to specific sections by simply circling them. When the candidate/student receives your comments, in theory they could lay the transparency right over their music and see your comments.
This reminds me of an interesting technique I first saw used by Eugene Corporan when working with conducting students. He had rigged up something that allowed him to hold a microphone and softly make comments that, I believe, were being overlaid directly onto the audio portion of the student's video tape. Clever but a bit cumbersome for a trombone competition.
One last comment on the ETW judging. This is my third time doing it. It seems that every time we end up with a choice between the more "clean, polished" rendition and the more "expressive" rendition. I will say that, usually (with one significant exception this year), the more expressive version wins the day even though it is often clear that the "clean, polished" player is technically stronger.
I have heard stories of parallels in big-time orchestra auditions.