Given how powerful they are, Drains are almost mandatory for some ships otherwise a target just shields and weathers your attack, but at the same time having your energy instantly drop from 100% to 0% sucks rather badly and is crippling to a ship.
Probably no ones going to like my idea but I figure Drains should be changed slightly.
Instead of draining instantly I think their debuff should completely disable Energy Regen(Including Energy gained from officer briefings, Modules could still grant energy since that's an active effect you have to choose to use.) and steadily drain energy for the duration of the debuff.
This would also allow the modules of different classes to have varying strength of energy drain. Single Target Torps could be rather potent, with Missiles just behind them. While Drain Pulse could be alot weaker in its drain strength due to its ability to hit multiple ships at once with it.
You can also carry this over into the drain effect that various Purge Modules utilize, it would give at least some brief time to react to the drain rather than instantly losing everything.
But that's just my two cents.