I'm currently about 2 hours into a game with this mod as well as a few others, and I have not yet expanded beyond my starting area. Despite making quite a lot of pollution (http://tinyurl.com/zsbre5c), I have yet to be attacked by a single biter. As soon as I go within 1 chunk of having vision on a biter spawner (which I have not yet done, including with the radars as you may notice), it immediately starts sending a constant stream of biters at me. This stream continues for about 5 minutes, after which the activity ceases and nothing happens until I go within 1 chunk of having vision once again. Subsequent 'activations' have far fewer biters attacking me, so I believe that the constant stream the first time is just the buildup of biters which should have gone and attacked me earlier, but did not. Additionally, when the bases stop sending biters at me, all biters on my map that are coming towards my base despawn and disappear.

My guess is that this issue has something to do with the biter spawners not being loaded by the game unless a player comes near them. So you might want to fix that, somehow.

Here are the save and mod folders:
https://www.mediafire.com/?ia5z5mblw0n8lz7

It seems that you fixed the ridiculous worm fields too, which is nice, lol.

I haven't checked your save yet, but can clarify a few things:

1. The biter stream is normal behavior, its a semi-rare type of biter attack that lasts between 3-10 minutes, intended to drain ammo/power. I know there is a bug with this, where when the attack 'ends', the biters despawn immediately instead of finishing their attack, which is what you saw.
2. Its normal for biters to not be spawned unless they are forming attack groups. Its part of how Misanthrope saves CPU. When you approach bases, biters will spawn to defend them, so its not required that biters always be wandering.

Shouldn't I have been attacked by now though, since the pollution is fairly large? I have tried just sitting for an in-game hour with my factory running to maintain the pollution level, and still no biters. Just to clarify, there have been no biter attack groups so far, which is what seems strange to me. It makes sense that no defending biters spawn, but there have been no offensive ones either.

edit: never mind, I did just get attacked. I suppose I need 10% evolution for them to become hostile, perhaps?

Yeah, higher evolution is important.