ECM swarms seem to be the new FotM.  The 300 range is what makes it potent, because it's way outside light weapon optimals. So you can easily be kited and jammed before they are even in any danger. Paired with a suppressor and you're pretty much dead. They'll likely easily lock break and keep you lock broken.

The best way to counter it is to fit ECCM and S.Amps, but even if that happens they're fast enough to stay away from you anyway. What sucks even more is that heavies are sitting with an 85 strength, so they're more susceptible to the ECM. I wouldn’t be surprised to see 1-2 light EWAR able to keep an HM ECM’d indefinitely and possibly even killing the HM if they had good enough EP.

To be honest I wouldn’t mind seeing diminishing returns on ECM. Or perhaps separating the potency of ECM from light and Med class by having 2 modules and toning down the range on light class jamming. If you want to jam a Heavy or Mech, you should be using the EWAR Mech imo and not some dinky little light. How a cpu system in a 25m HM is worse than that of something like a 500k assault is beyond me, but apparently it just works and ECM is likely going to turn in to the next most complained about fit/tactic.