CaptCastrin:
That's exactly the sort of information I was looking for to satisfy my curiosity. Thank you for taking the time to answer.
Too bad about this being non-revertible in the patching process. Time for me to go design workarounds. :-)
Early era is not too hard, you can (as DH pointed out) just boost the price of faster drones to 1,000,000 a piece. That way no one (except Fluf) will be able to afford anything except the free slow drones.
Mid era is harder, if you want/need a longer mid era. How do you price fast drones out of reach, without making medium speed drones too expensive? This might require new mission scripts to put an override on drone speeds. <pondering..... pondering.....> Of course, you have a longer hard-coded mid era than short era, so you've got time to adjust FYA to space ship releases. You could always just set the number of turns per year longer in mid era and make it last as many real-time days as needed.
Anyway, thank you again for your informative and helpful answers.
-S'Cipio