Right now the explanation for the tech nerf incompatibility is the lack of proper maintenance/spare parts. but the actual tech nerf seems a bit ... lazy.
so here's what I've come up with:
1. you shoot down a liberty police in your freelancer fighter and loot his cop gunz
2. you mount it, but oops you only get 10% compatibility or something
3. so you go to a libertonian civilian base/planet where you know a mechanic that will repair/restore compatibility for anybody, for a huge fee
4. you pay the mechanic, and he helps restore as much as 90% compatibility between your new liberty guns and your ship
5. you maintain this level of compatibility until either 1) the gun gets damaged or 2) you unmount the equipment you had previously restored compatibility for or 3) you get your ship repaired at a non libertonian base (restoring compatibility for another faction will not further reduce your power core output)
6. When you lose the compatibility, you just revisit the libertonian base to restore the compatibility. you can do this for all equipment
No atmosphere? GTFO.
The propeller is the greatest invention of all time.
The nerf system is there to apply consequences to incorrect RP. Having what you suggest would make RP redundant and you may as well have a Vanilla server where everyone flies nomad and Tizona Del Cid setups.