Come to think of it, isn't AC + Ruthelessness (plus I'd probably go with EU) a great combo even without Cluster Missiles? It's gonna be a guaranteed three hits per turn quite often, especially against swarms.
How are you figuring three guaranteed hits? It will be two hit results every shot and if they aren't both canceled will cause damage to a ship within 1 of your target.
Ah, true, that third hit is dependant on the other two not being dodged. Still sounds good to me, I'm looking forward to trying it. It reduces the randomness quite significantly, though not, as you pointed out, completely.