I'm not seeing the difference, as it would, at most, come down to your "attack craft" carrying more fuel, at the expense of either weaponry or armor. However, as pointed out by others, the cost/benefit to armed small craft really stinks, because they get almost none of the free equipment handed out to ASFs, making it very difficult to produce an armed small craft that is more useful than a fighter.
Given that your inspiration, the LACs from Weber's HH series, were originally short-ranged defensive craft, I think the Lyonesse and Aquarius are exactly what LACs up through Honor Among Enemies were portrayed as, and it isn't until LACs were given fission (vice fusion) powerplants and side/bow walls that they ended up as anything useful. Short of a similar technology being created at the staff's whim, I don't see armed small craft growing past their limited existence.