As I posted in the Battle Report folder regarding A-Wings. What I like the most about the A-Wing is Boost Action. Combined with it's zippy maneuver dial, boost action allows the ship to dance around the opponent, staying out of firing arcs while bringing others into your sights. Every Pilot card has the missile upgrade icon and two out of the four have the medallion upgrade icon. Truly the only thing missing from the A-Wing's action bar is barrel roll, but it's not necessary to add via Expert Handling.
The other thing I like about the A-Wing is it's Shields. I'd rather have a point of shields than an extra point of hull any day, because a critical damage to a shield is like water off a ducks back. Also, though it is seemingly less offensive when compared to the X-Wing, it's greater ability to position it's self in the battle space allow for more opportunities to fire as opposed to fewer times with greater success.
The best A-Wing to me is Arvel Crynyd. His Pilot Ability combined with boost action allow me greater control of engagements and make me less likely to be concerned about getting in close. He is also great for making the weak primary weapon more effective, by staying in range one of the opponent while using boost action to take away their ability to fire back. Although his lack of a medalion icon may seem bothersome, the missile icon allows him to make up for the weak primary weapons at greater range (even if for only one attack).
The A-Wing adds greater depth to the Rebel Fleet making any build more versatile. I agree that it can function well in support but also feel it has offensive capabilities given it's extreme maneuverability.