I am kind of surprised this issue hasn't been brought up, but I will do so now. The demo's with ullapools can easily ruin a map for hale. Some examples I will provide are Missing, where demos can jump up to the top of the walls by the moving platforms, go around the trap, and hit the button on the other side allowing everyone else to go around the trap. Example two is on Factory, demo can ullapool by the sentries and safely jump all the way across them to get to the other side and win, avoiding all 3 of the sentries. Example 3 is on mario, where the demo can ullapool to the top of the platforms at the very end, and just run on top of it all the way across to get to the other side safely.
My suggestion is that the ullapool gets nerfed so that demo's can't jump as high, as removing it will most likely get a huge group of people irritated.