100 % true , for example mp_col1 zombies can never kill all the humans when they camp on glitches , (yes never!)
Whenever I've played col1, zombies are still able to reach the glitchers after a while, I don't see why it should be easy for them to glitch up after just a second, requires some effort and team work. Zombies can win col1 as much as any other map if only the first zombie is good and fast enough to get a few team mates, the round time limit is 4.
M4 cages should be removed for less high boosting. This way, you would have enable small roofs that require 1 or 2 man.
Max, if it takes you 5 minutes to add around 50 objects for all my MP maps, then be my guest and add those.
Also, can you imagine how it is to play mp_pra1 without the roof glitch? This makes the map 2x smaller and way too hard for humans if they are only a few against 20 zombies moving around those small alleys. Same thing goes for mp_hos1, without the boosts it's a very tiny map, would be easy for zombies to overcome all humans on the ground.
You don't need so many different maps on the server: just start with fixing 4 maps and then gradually add more maps at leisure. And removing mp_pra1 as a viable map isn't such a big disaster, is it? Simply only use big maps such as mp_kam1 and you're golden.