Again, I feel I must emphasise how strongly I feel that any combat related performance improvements crew gives you IMHO risks just creating The Engineers pt2!
For me The Engineers has (needlessly) unbalanced the game. It created a mindless go-to upper tier of performance with little/no thought/consideration required. It also made already somewhat rock-paper-scissor combat into rock-paper-scissors-lizard-Spock combat.
Now with this crew proposal seeming offering more performance perks, we raise the performance bar yet high, and seemingly add in a few more assets to confuse our now already rock-paper-scissors-lizard-Spock combat.
I too like the idea of having crew onboard with the premise of them adding to personalisation of the ship. But the premise of them simply being The Engineers pt2 alarms me.
Hence my earlier suggestion that ships maybe that can have crew would be at a disadvantage without them? eg: If you're off exploring/exploring it's up to you whether you take crew with you or not. If you don't you're saving CRs but some aspects of your ships performance may not be as good (eg: less effective shields).
Ultimately I just cannot see combat related performance being improved by crew yet again (on top of The Engineers) being anything other than further messing up combat.
For me the trick would be having crew be an asset, while not needlessy raising the combat performance bar again, and creating even more rock-paper-scissors combat mechanics.
Obviously it's a different type of heat