...just a random thought here, not a fully-developed balance opinion.
Essentially, make Weapons and Hull Mods slow acceleration and turn-rates a little.
But:
1. It'd give a good balance reason behind evening the OPs for ships, which the game needs (half the ships are basically just wallpaper because they lack enough OPs to be viable, not because their base stats are so bad).
2. It'd encourage another form of min-max; keep mass loads light to keep a ship speedy, or accept more mass in return for firepower.
3. It'd provide another balance stat that might help make the out-of-sequence weapons balance better (in particular, it'd help balance Mass Drivers, Light Needlers, etc.- the weapons with absurd range bands and overall combat power for their slots).
4. It'd discourage players from simply piling on lots of guns and Hull Mods at the high end, where Skills compound the power. I think that, no matter how Skills get re-balanced, that they're going to still provide that heroic edge (if they aren't nerfed into useless noise) so it'd be nice to have a factor like Mount Blade's weight system for equipment, where more is better, except when it's a foot-race or you're trying to close on a castle without becoming an arrow-filled pincushion.
