We played Highpass in a New Map Weekend pug. It was a really good play and was fairly balanced for a 72 hour mockup. Aside from the problems that you know about (the door on the left on the sniper house and the visibility issues concerning the walls in the little caverns), we only spotted three real things that could use improvement.
1. Widen
this little area under the point, but not by much. Right now it's so narrow that the risks using it totally outweigh the rewards for it. Maybe even put a health pill or pack there.
2. On the point of health packs, we felt that a health and ammo set
in the cave would make it both a viable push, hold, and retreat area.
3. From the sniper houses, you have extreme visibility through the cave, while the hill is relatively protected. Suggestion was to put some blockage to obscure the sightlines for the cave slightly.
Other than that, the small map size gave us the feel that this is what a map like Viaduct should have been. Most competitive players complain about the heavy's ability to negate jumping soldiers and demomen completely on Viaduct, but heavy was both viable AND punishable on Highpass. It was similarly with gunslinger engineer. This works in tandem with 24-man servers where players who prefer playing pyro and/or spy will enjoy nice hiding spots and engineers will find much to do in terms of defensive and supportive sentries. With a little work, everyone will enjoy playing Highpass. Hope you enjoyed the feedback, because we enjoyed the map!