Yeah, if you check closely you CDs you will see that the torpedo doesn't actually go into cd, just into a fast cycle. The graphic goes off but you haven't actually fired. The last torpedo you fire is actually the only real one.

It is a bit bothering with HYT because sometimes this thing will eat your HYT and you're left with a single torpedo instead of the full salvo, but can't do much about lag.

Stick with III, and put beam overload/fire at will I and equip one beam. Overall, your burst/dps will increase and you will avoid shared cooldowns.

I guess i'll try that and see how it goes.