In the scheme of things at this point, him complaining about your rooster won't get him far. You're not taking into account a very LARGE point- these dogs killed another person's *50* chickens. This isn't about loose dogs coming onto property anymore, this is about dogs that have a history of drastic chicken-clearing & is trying to do so again, while said owner refuses to deal with the problem. It doesn't matter at this point who calls whoever, his bill to the other neighbor for the 50 chickens should be enough to shut him up!
I would personally encourage the other neighbor to call animal control or the police about the loss of his flock, whether he wants reimbursement or not, it should be reported for when you guys do call & try to get something done (because I'll bet, with all the dog owner's 'concern' about his running dogs, they'll be back shortly).
Also, about the electric fence, they don't electrocute people, or kids. It's a sharp little zap if they touch it & I can tell you, they won't likely touch it ever again. It certainly won't "hurt" them other than a startle. I would surely not hesitate to put up electric fencing around kids- & I've got some of my own!