Just whining without having read anything else in here.
1. There's an exit sign in the spawn room that feels completely unnecessary, since there's a giant door and it's literally the only way to go and you can't even get back in here anyway. I personally think you should not to oversign things, but no biggie if you leave it.
2. You might want to add a clip plane/clip players when the door closes, because you can get caught on the frames of the spawn door.
3. Playing a pyro now, I can't tell if you're supposed to be able to get on the orange ledges to the left and right of the spawn. It's alllmost jumping height, but I can't make it, or it's clipped.
4. There's a penguin fisheries sign on both sides to the left as you come out of spawn, and in this area, there's 3 wooden door frames that are exactly the same. I feel like it's unnecessary and part of that should just be a pillar, if anything? It's like the tiniest possible room before being outside. It just bugs me.
5. Dunno if it's just me, but the area with small health on the left/right sides feels like it should be raised so I don't have to crouch just to get back up. Not sure if you did that to make people less likely to go over there or what. Having to jump up is fine, but there's a possibility that someone will jump and not crouch, then have to jump/crouch again, which ruins their flow, if you knowwhatImean.
6. Actually a lot of these arrows feel unnecessary. There's one on the ramp that just points down at the opening that's obviously there. (If you go up the ramp and turn around).
7. Also, up that ramp, if you look to the left side there's a stack of crates and you can't jump on those. It's weird. Also, if you jump down to that orange ledge I mentioned earlier, you can't because there's a clipping plane here. You should probably raise the ledge off this direction so you can't make this jump? Or put some nice trees or something. (But you said dustbowl stage 3, so I dunno)
8. Also, that ledge where the ramp is seems a bit too tall. If you're trying to Spy and have someone following you, it would be really cool to smoothly jump over that ledge behind the guy chasing you instead of clumbsily crouch jumping onto it, then running off the ledge.
9. In the cap building, the little ledges you've been consistently using outside is used and I really feel like you should replace it with a metal prop so it's more catwalk-y. You're probably planning on doing this.
10. It really sucks to jump to the middle beam at the top of the building for the small health and have to fall and take fall damage. You can't jump back the way you came, and you can't comfortably land on any of the walkways that are elevated unless you walk to one side and crouchwalk/slide. Dunno how to fix this, so you might be okay leaving it the way you have it. Maybe make the healthkit a medium one so that you actually can have a netgain in health if you go in with ~1/2?
11. I don't think the paths on the far far right and left (with the full ammo) get used that much currently because there's really no cover here at all. If you want it so they still have a disadvantage by using this area (other than the fact that they're lower than everyone else in the map), perhaps give them something small to use for cover, like a barrel or small rock? Just so they don't get mowed down too easily.
12. Can you make the far far right/left buildings w/ full ammo slightly lower? Mostly so that when you back into the stairs that lead into them you automatically walk onto the steps instead of stop? Also maybe move the walls back or clip them so that you can casually walk into them backwards while firing the opposite direction? I ran into that corner at least 3 times during play and gave up on it.
13. Underneath the spawn area, there's a bunch of pillars and some boxes. Navigating the box/pillar part is very terrible because it looks like you can fit with just a small hop, but you hit the lantern, pillar and the top box and it's basically terrible.
Yeeeeep.