Please don't add a shield to double chevron bases. Really? I think people will not even bother unless they have a death wish. That's for going in commando style. Why bother, walk away. It's missing the point. Your not taking down a base shield with a shot gun to take out a sentry.
Shields are fine on admin bases, but the shield generator either needs to be able to be disabled or destroyed, or the shield set to not regenerate in the playfield files.