I remember a couple of years back Cerium and I and probably some other people tossed around the idea of having items more tied to physical characteristics like power and mass and thrust and things of that sort. For example the Warbird could have capacity to hold 1000 kg of equipment, energy/recharge would be calculated based on the reactor load, etc. In theory even with an inferior engine a lighter ship would be able to outmaneuver the same hull if it had more stuff in it. Of course coming up with the physical model and balancing it would be considerably more complicated than even our current system.