So.

I did:

-Minimum shield mitigation increased from 20% to 30%
-Maximum shield mitigation increased from 60% to 80%
-Mitigation gain rate increased from .001 to .0015
-Mitigation decay rate decreased from .0125 to .01

and it was amazing the impact it had on the game. Fights lasted longer (well, they would have, but my slightly too modded Gauss Blast was the hammer of lucifer so far as frigates were concerned.)

But the most interesting thing happened when two Kols went at it. Any attack heavy enough to threaten a Kol rapidly jumped shield mitigation to 80% and they just lasted much longer than i expected, even a slightly nuts fight that me and a marauder fleet attacking a planet at the same time.

The downside was that having an effective 10000 shield points or so (consider regen) means your 4000 hull points go rather fast.