There's no need for visual evidence. S4w is correct. The emperium takes 1 damage per hit. Most of the beta testers already know this but it should be evident when you see FSK stalker or 190 aspd clown (spirited guitar) beat an edp'd sinx on the emp. I've capped a ton of emp solo on my sniper with 190 aspd by punching (because it is much quicker than having a bow out which drops my aspd to ~184).
While we're on this topic, it is the same for barricades, guardian stones, and the flags in bossnia mode. The only thing that is different are the bosses in the bossnia map which take actual damage.