I had a few ideas for balance, but I know it will just get flamed and shot down since there should be no limit to the kind of idiotically powerful ships one should get with 5 billion credits....right?
I'll try to make it as short and to the point as possible to not bore you with too many details -
Scanners, Tractors requiring cargo space to equip. Better scanners would require more cargo.
The more sturdy the armor, and the more power generated, the less cargo a ship has.
-Low tier Light fighters would have the most cargo. Light-sparse superstructure, so more room for sensor equipment.
-Large fighters would be solid and tough and packed with the equipment for high demand weapons and cooling, but very little room left for a cargo hold, and thus, weak sensors.
Allow all class of fighters to use all class of weaponry - The limitation is still there that weapon power requirements of class 10s would drain a light fighter in 2 or 3 salvos.
Now look at the Patriot and the Liberator - How is one 10x times better in all respects balanced?
Why have multiple tiers of a single fighter class?
There needs to be a shortcoming somewhere... 1% less agility isn't enough.