Yeah, I think a lot of people that struggle to beat the Karists with Epirians are probably not using the Aerial Drone Strike at all, or not using it to its full capability. It is a really powerful ability, particularly when the Journeyman Bot Handler is joined to a full-sized unit (like Contractors or Spider Drones) so that the damage caused by the Aerial Drone Strike stacks with that caused by the rest of the unit's shooting as well. With a large blast, you're pretty much guaranteed to cover ever model in the target unit, so if you're targeting a full-sized Karist Trooper unit, for example, you should be getting an extra 9 shots with the Aerial Drone Strike (on top of what the rest of the shooting unit manages to accomplish).
Oh, and I should have mentioned in my last post that there are a few abilities that do specify they don't work when wild firing. The 'Burst' and 'Paint' abilities being the two that come to mind.