Only healer who can take all three is command0. Energy shield +aoe reduction and heavy armor brings the damage down to slightly less than lethal if you're at full health and have like 50k+
I found as a scoundrel with revitalizers and AOE reduction I can take 2 (~21k apiece), so killing one would work. We never tried to kill a single one and that is a pretty great idea.
While I'm okay with it staying as it currently is (especially since we'll be able to survive it with more HP/Armor), the mechanic is the same lazy 16man design we usually see (hurr just add more of it) and could be improved. I'd be in favor of having more pairs of load lifters which can't aggro on same person. Maybe 3, aggro'd on three diff people?
As someone who has been surprised by them spawning under my feet and died, this is not correct. You still take full damage.