At the moment the support frigate doesn’t seem to be very capable, compared to the vehicle it was in HW1 it is a pale shadow and I personally have tended to use repair corvettes for augmenting regen rates. In the original game the repair at range ability allowed the ship to stay behind the fleet while repairing as well as letting it rapidly switch from one repair target to another.
I was thinking it would be a decent and relatively true to the original change if the support frigates repair ability was changed from an active one to a passive area of effect style one, similar to the fire control towers for HW2 ships. Over a reasonable range it would boost a ships regen rate by a certain amount and could stack up to 3 times. The repair rate would obviously have to be lower but it would also help differentiate it from the repair corvette and make it more than just its big brother.
It would also be pretty interesting if they were given an active ability that prevents the launch of docked strike craft. That would let it act as a hyperspace carrier which would be able to deploy ships much faster than a conventional carrier.