Love in-depth feedback like this!
The changes to the turret would probably help a lot! They do seem a little weak especially as the game progresses. I really struggle to balance my games actually. Other than play testing, I wonder if there are some rules of thumb I could be following. Need to do some research!
The plant variant idea is great. I tried having the drone lasers hit all objects, but that opened up the strategy of sandwiching yourself between a bunch of plants and not worrying about drones at all. Plant variants would really open up a lot of possibilities.
For the rooftops, I originally planned to have zip lines between them. The idea would be you create a little plant growing engine with turrets protecting them and then move on to another rooftop. But then... suddenly it was Sunday :( Still recouping from my sleep loss haha.
Happy to see you noticed the slight vertical auto-aim :D