While I like the idea of how trade is conducted (with the mini freighters etc...), it has a major drawback:
if you want to play correctly, you should, during a war, kill all of your opponent's trade routes.

You are at an unfair disadvantage against the computer here:
- it knows exactly where all the mini-freighters are (just strain your eyes on the map in GC1 to get that information!)
- It can (and does!) shadow some/all of your mini-freighters with small attack ships (try to do this against the computer and tell me this is not micro-management pushed to the limits!!!)
- it can do this painlessly, every turn.

Hence, I'd suggest that economic warfare be treated in a more abstract way:
- create "pools" of attacking ship for each route (which role will be to attack that enemy trade lane)
- create "pools" of defending ships for each route (which role will be to escort that trade lane mini-freighters)

Now, each turn the computer would have the responsibility to move the ships to/along the trade route., either attacking or defending the mini-freighter.

Now, to attack an opponent trade routes, you only have to put ships in the appropriate pool. Same thing to defend yours. The ships which belong to an escort/attack pool should appear differently on the map. The only difference would be in their movement/management: a ship put into a pool would automatically attempt to attack/defend the appropriate trade lane mini-freighter.

It might even be possible not to select a specific trade lane, in which case the computer would decide which to defend and which to attack (based both on the distance to move to a given trade lane and how well all trade lanes are defended). This would just appear as a new action for ships (just as sector-sweep etc).

Yves