What's the justification for the Vanguard using an Interceptor dial? It was conceived before the interceptor engines were devised. It's basically a souped-up TIE Fighter with a cheap shield generator and an advanced sensor suite- probably powered from the surplus energy from that missing laser cannon. Wookiepedia says the TIE/RC was somehow more maneuverable over the standard TIE, though I feel the best way to represent this is to give the /rc the ability of generating two dodge maneuvers per action.
I guess I can understand the reduced agility of the /gt, but bear in mind that it is not lugging around two over-sized pods and longer solar panels. Mass is a consideration but not a handicap. I'd say take out barrel rolling and give more red movement points for extreme turns, as well as reducing the attack to 1 (for one laser as you say), but otherwise keep it close to the TIE fighter for which it's derived. Give it one torpedo slot for the limited magazine and would allow it to carry bombs.
Why not let the /fc take advantage of it's own advanced sensor suite? It's not going to be doing much with it on it's own, except allowing you to re-roll your one die at like a maximum of two times (three if the sensor suite gives dual sensor locks), but the most you're going to do out of it is two damage, and that's IF you have a critical, and IF it is the 2 damage point card, and IF the target has no shields left. Make an equipment item for targeting suite, allow it two target locks for one action and to give to other fighters, then say "Restricted to TIE/fc, TIE/sc, TIE Vanguard, and TIE scout". None of these fighters are going to be front-and-center combat roles and are really there for only fluff or interesting support options that aren't reliant on hero space pilots.
Ideally these scout and fire control fighters would be hanging on the fringes of the battle and enhancing TIE swarms until they're shot down. They'd be prime targets, but that isn't so bad because your support fighter would be your weakest hitter.