It seems that Raiders, while dangerous, are pretty reliant on their tech edge. They certainly aren't unbeatable, and killing/capturing their ships should lead to a pretty rapid evening up of tech levels if you can salvage the wrecks, or choose to disassemble prizes. Of course, it being so early in the campaign, the Imperium is having trouble using the improved tech, because Gallicite shortage is a thing, as ever (and we haven't even GOT to the Corundinium Crunch yet), but if they can fend off this early pressure, it should mean a much stronger Imperium in the medium term, with access to much better engines, sensors and ELINT gear than you'd normally expect.