An idea for the two different Level 2 Geo-plants:
At the moment, they are very similiar I think.
Maybe the 'dangerous' version (forgot the name) should have an "high pressure" option that can be toggled via the on/off button.
When enabled, all safety valves are closed and the energy-output is doubled.
This would result in a bigger explosion when destroyed (better switch off your plants when attacked!) and the self-repair would be stopped.
I think it would be a good experiment to try turning Twilights and Exploiters into an actual upgrade to regular extractors, rather than just an alternative. They will have an increased metal output compared with regular extractors, but will still make moho extractors the ultimate solution.
This might get too complicated...why not just build some extra windfarms+metalmakers, although short-lived they are usefull to make the jump to level 2 a little easier.