I like current mechanics, because it gives you a choice between adsorbing last shot and overloading or tanking it with hull/armor.
With automatic piercing there won't be any choice - only check whether your reaction is good enough to disable shield in time.
The only thing i'd like changed about overload is how easy it is to provoke AI ship to do it. Keeping shield up till overload against combined stream of small kinetic + HE projectiles just doesn't make any sense...
