@darkfrei, it's nice of you to fulfill a mod request. My critiscism is all meant to be constructive and helpful so that your mod can be as good as it can be.
I do wonder though why you decided to post this mod hours after I had posted my mod. Of course you could have started it earlier than me posting it, but I had discussed feature list, implementation details with specific APIs used and with testing results making it pretty clear that I was working on it too. But your mod doesn't use the any of the info I released on how I would make the mod which is a bit Qonfusing to me.
So after I released my mod you decided to complete yours and post it. Of course different people can post different mods and people can choose which version they prefer. Different mods can suit different tastes. But I haven't seen any feature that Evo has that mine doesn't. I would say NGE does evolution scaling better since it follows the vanilla behaviour and the settings values mean the same in NGE as in vanilla. My mod uses the stats Factorio already collects which means precise values even if the mod only does a tiny amount of work once every minute. Evo collects data via APIs that I believe to be more expensive and it has to do it every tick and it still can't really keep up with the data produced. So while Evo doesn't greatly impact performance it is still like 10 000 times more performance intensive than the solution NGE uses and it's only really fast because it doesn't try to keep up with the pollution cloud statistics and just makes an extrapolated approximation instead.
Your mod isn't configurable. That could of course fairly easily change. But the other stats like trees damaged by pollution isn't really measurable with the way Evo is built.
The wiki has great info on how evolution is supposed to work:
https://wiki.factorio.com/Enemies#Evolution
It provides formulas and other great info. I used that article to learn how evolution works in vanilla so I could make the formulas in NGE "correct".
Vanilla pollution evolution curve:
The formula you use give you a linear graph line. That means you go from from 60% to 100% just as easily as you go from 0 to 40%. But the difficulty of the evolution changes much more from 90% to 95% than it does from 0% to 40%. And you typically release much more pollution later in the game. This means with "Evo" you might get from 40% to 100% faster than it takes to get from 0 to 40%. So you might see medium biters and when you try to research solar and efficiency modules you get max evolution immediately.
The spawning probablility graphs shows this:
Compare the area of the purple of the small biters to the green of the behemoth biters. Behemoth biters start at 90%. And with vanilla evolution you never really reach 100% evolution because it increases slower the higher you go. And the effect of 1% unit more evolution is a noticable jump in difficulty when you reach this stage but it requires quite a bit of spawner killing or massive pollution to actually happen.
So a different evolution curve is maybe preferable to some, but most would definitly not want it changed to linear without being told about it. Unless they are doing a specific challenge run where they want exponential difficulty it's hard for me to see any benefits so I'm assuming it's an oversight by you.
So finally is there anything that your mod does that makes it a preferable option to you? You decided to release it so I assume you prefer something about it?