I found this map to be pretty fun. I do think there were far too many people on the map, but it would play fine with 12-12. My only complaint is that it seems far too easy/common to spawn camp because of the main door right there. Obviously when people spawn up top they'll naturally just move across the top and shoot at enemies they see, which means they'll be shooting directly into the enemy spawn.
One possibility would be to raise the spawn room, making the space directly in front of it a 2 story room with a set of stairs leading to the spawn room. While it would take a bit of work, it would prevent rockets/nades/heavies/pyros from shooting directly into the spawn as they're running past.
Another option would be to move the spawn room back about 20 feet (not sure if it's possible... I didn't look at what's behind there) and possibly making a glass wall around the current stairs (the 3-4 steps coming out of the spawn). That would give people leaving the spawn a chance to see if there are spawn campers outside as well as give engineers a slightly safer place to build teleporters. It would also be a nice spot for a sentry guarding both the spawn and the entire upper path. This is the option I prefer.
Finally, you could just move the spawn wall back a few feet and make it the same window style as the ones overlooking the intel. That would allow people to see out before they exit.
I don't know if it has been a problem in other playtests, but if so then hopefully these suggestions will help. If you need me to sketch out any, let me know.