Allow Civilian fleets to use Conventional Engines. This would allow effective early colonization for Conventional start.
/Yes, I've moved infrastructure to 3 promising worlds with a conventional freighter by year 5, and can't afford to build a colonizer due to Mercassium shortage. TN tech is expected in just over 10 years. I was banking on a Small L0 popping about 2 years ago.
For the record, the only 'cheating' I did was swap out the starting Naval shipyard for the equivalent Civ shipyard so I could build my freighter.
On a related note, ships (and missiles?) do not lead their targets when navigating. This means a slow Conventional powered ship can get stuck chasing an inner planet because it can't catch it, and isn't smart enough to go the other way. It could also prevent slower ships and missiles from intercepting faster targets that would otherwise be reachable.