Just a random thought, but as someone who can't play with mods anymore, I don't understand why new ships seem to be added so conservatively - I came back to this game after many years away and could hardly see a difference in the ship roster (without mods, as I said.)
I'd really like to see more unique ships all around - one battleship is great and all, but thats like, a drop of water to me!
Regarding the SD, I'd much rather see a focus on a doctrinal insistence on certain tactics/loadouts rather than "flashy but useless." Solar shielding? meh. I'm thinking more like the Empire in Star Wars with its focus on crappy Ties and big guns, etc - unique systems and that sort of thing maybe. I don't know, this is a neat idea I guess, but it seems pretty boring all in all.
Last note in regards to the Orion Drive, my introduction to the concept was the book Anathem by Neil Stephenson - highly recommend