For space combat, I believe shields need to be tweaked. Several squads of bombers can take out the shield generator fast, leaving the rest of the ship vulnerable.
Perhaps when shields are 50%-100% torpedoes only do 50% damage and the rest to shields. Only when shields are below 50% then do torpedoes and concussion missiles work as they do now. Otherwise, ships will be fighting shieldless most of the time if the opponents are any good.