What do you find to be the most efficient use of your secondary weapon options? Personally, I've had terrible luck with Proton Torpedoes. I always seem to whiff. And I typically don't like spending points on one-use items. Whereas Cluster Missiles always seem to come in handy. I can't wait for the A-wing so I can (presumably) use them with Rebels. But in my limited experience, it seems targeting choices are very important here. And the better option seems different for each faction.
For example, with the Imperials I've found it best to pick out the one target that most worries me and just pummel it with any and all Missiles at my disposal. Most of my attacks for the game are going to kill through attrition, and it seems worth the resources to score that one all-important quick kill.
Now, with Rebels, I find that I'm actually better off using my Proton Torpedoes on the scrubs. If I can take a weak TIE out of commission (either an outright kill or hampered via Crit) for each Proton torp, then I stand a much better chance over the long haul. Using them on Vader or another high priority target usually doesn't pan out as well for me. He might well survive, and then I've wasted my opening volley without diminishing my opponent's attack strength. Also, I've lost a game or two because my opponent held a torp in reserve until the endgame and I forgot about it, being so accustomed to them all getting used so early.
So what are your thoughts? How are these best used, and in what quantities?