I used them for practically the first time recently and they seemed to automatically change targets whenever their current target was stunned. Which was a good thing, as it meant they stunned enemy groups maximally. However, it did mean individual enemies would sometimes blip out of emp, since they didn't accumulate a lot of emp charge. I guess this behavior might be bad if you have more gnats than enemies, but its definitely good if you have less.
I moved them in line formations and attacked using line fight commands, as I do for almost everything.