Blinking does leave you open to return fire for one turn, but it will not be obvious to the enemy which turn unless you are predictable in your tactics. This is a significant difference from not blocking LoS, which would allow you to shoot out but enemies to never be able to shoot back in.
Blinking shields will cost even more CnC than gunports, since you've gotta blink or lower ALL the shields on your ship.
I figure the cost is going to be about 10-15 for the big ships you've got. More like 3-4 for a fighter. Which means any ship should be able to do it, but it will cost all of the ship's CnC focus to accomplish, leaving little for guns/repair.
Currently, it is legal to blink the shields, but you have to edit the PLR yourself to do so, and nobody has yet bothered.
Or, if you have double the shield coverage on your ship, you can have group A enabled, and group B disabled, then disable As and enable Bs as you detonate. Both shields will be down for the turn of the blast, but you'll have the B group up for next turn.
The same principle would apply to having paired gunports and swapping between the two each turn.
I could also modify the server to disallow enable+disable on a single component in one turn, but I'd prefer to simply change the turn order to have both enable and disable either before or after the fire phase. Not sure which.
Before would mean you could defend by snapping the shields up only after you see the enemy is aimed at you, and keeping them off the rest of the time. You could take snap shots through your gunports as they open, and surprise-detonate EMPs as you drop your shields.
After would mean you would get an extra turn of protection from shields and not have to pay the energy upkeep for the turn they drop. (You'd have pre-paid it when you raised shields without getting protected the first turn they rise tho) You'd have to wait a turn for your gunports to open and shields to drop before safely firing weapons or EMPs, so no surprises.