Difficulty absolutely effects power consumption. Has since FS1. Load up quad banshees on a herc, set it to very easy, you can fire all day. Set it to hard...well, firing all day isn't gonna happen.
I'm actually inclined to loading up an areas with quad maxims and dual kaysers in the last mission. Just seems most quad guns end up missing 2/4 shots when firing on fighters anyway, so I just use the duals, and save the quad guns for ripping into easy to hit cruisers with the maxim.
Eh...do the hornets/tornados work well for other people? Tornados don't seem to fare too badly, though not great, but hornets miss entirely too much to be useful, imho. Not when harpoons are available.
Actually, most FS1 weapons had that issue. Ended up being practically dumbfire dependent except when bombs are required, and even then I was cursing them for not having a dumbfire heavy rocket ala tie fighter.