SO i had an idea while playing sins a couple nights ago about a new type of star system defense.
In essence for planetary defense you have largely immobile defenses. In one of my favorite book series there is something called an LAC or Light Attack Craft. these are in system ships only, typically used for defense, they cannot phase jump.
I propose a set of system defense ships which would have relatively the same strength as the gauss/missile/defense platforms but mobile. They would cost 1-2 points each and would be exactly the same as a defense platform, but as if some redneck strapped a rocket onto it. You would be able to move the ships around, like a regular ship could(possibly with a weapons damage penalty for it moving) , and you could also "park" it in a location like a ship can be when you change the attack radius.
My reasons for wanting this are that it just kinda makes sense. They would take away some of the advantage or missile frigates, but not all of the advantage, There could also be a script inserted which would only allow the ships to be moved by the player, and they couldn't just move of their own accord.