Looking at the shields the badge vendors offer, to tide me over until something better comes along, I wonder what is better: A big thick shield with slow regeneration (covariant), or a weak shield that regenerates rapidly? Both have directly opposing strengths and weaknesses. A covariant shield would probably expose the weak hull of an escort less often, but for longer periods of time, whereas a regen shield would expose the hull more often, but for not nearly as long.
With a regen shield, you can hope that a weakened shield regenerates before the enemy gets many shots off at you. With a covariant shield, you can hope that it lasts long enough so that an ability like reverse polarity or science team is off CD when you need it.
So I'm not sure, and I would like to hear the opinions of all you escort experts!