[MrToxin]

Well, this is what I did with SEIV with the mod I never finished (I'm translating it to SEV because it will work so much better, but I still might never get around to finishing it). Some of these ideas may or may not work quite right, as I haven't tested all of them yet.

First one is to use Quasi-Newtonian Propultion. That is a lovely, lovely idea. I set thing so that the biggest ship in the mod (Worldship) was set to something around 230 engines/move. Yes, it was massive, but it could barely move. Because Frigates had 2 engines/move, with the top engines being tremendously small (I forget exactly, but after a few million research points they got you around 1.1 move per kT of engine), they could essentially teleport around the universe while the Worldships chugged along.

Frigates got a 40% bonus to hit and a +50% defense, while the Worldship got -90% to hit and -120% to defense. The Frigates could hit the Worldship, but it didn't have a prayer to hit the Frigates without point defense or tracking turrets. However, the Worldship was over 100 times the size of the Frigate. Because higher-end armor and shields had massive amounts of damage resistance compared to tonnage, the thing could just sit there and ignore a Frigate. It's a stalemate, making a variety of ships useful.

That is, if the Frigate ever engages the Worldship. Chances are, the Frigate will maneuver around it. Fleets of smaller ships become skirmishers, while bigger ships fight over planets.

At the same time, Mounts become larger as they get bigger, but also tougher. For example, I set Large to double damage, one extra range, double tonnage, and thrice the structure. It gets a -20% penalty to hit, too. I can be stuffed on any ship that can handle it. This allows for extra fleet customization, as you can make a bunch of Frigates with a single giant gun designed to punch out larger ships but will have trouble with other Frigates, while you can also use Light mounts or even Tracking mounts (big, dont do a lot of damage, bonus to hit - essentially a mass of gyrostabilizers, servos, and targeting gear) on a massive ship to make it an anti-small ship platform.

At the same time, I was experimenting with specialized crew quarters. Things such as officers, engineers, and what not. The specialized quarters are twice to five times the size of regular ones, but give various bonuses. Obviously, a Frigate will only carry one type of crew, which limits the bonuses it can garner from them. The Worldship, however, can carry a LOT more of them, getting bigger bonues. Considering that there's more ship to apply the bonus to and more ship to stuff quarters in, the big ship gets the big gadgets.

This is going to need some extensive tinkering and testing, but it's what I'm up to.

edit: Another thing I'm looking at with SEV and its formulaic stuff is giving specific ship types different bonuses, rather than giving defense bonuses to everything a they get more advanced. Frigates would get maneuverability and defense bonuses, but no extra kTs of space, while big, lumbering ships would never get a defensive bonus, but rather extra tonnage. I'm also thinking that adding Destroyers would be interesting, which would have to be mid-sized ships that get a bonus to hit, making them specialized at taking out smaller boats.