I agree, a good dog to have around is extremely effective against most predators. My border collie mix is so smart that when he hears the roosters give the "hawk alert" noise, he looks upwards and takes off after the bird...most times it is a vulture but you get the idea. He is also very vigilant at night. He sleeps inside but the slightest noise and he is whining at the door. If I let him out and there is a predator in the woods, I open the gate and off they go...when it does happen, I am sure to set the trap the next few nights. Last year I caught 15 opossums and 6 raccoons.I have had coons as well but not lost a single bird to any in nearly 2 years to them. Dog and I have killed three adult raccoons this spring alone and lot more oppossums. Dog does awsome against red fox and even keeps coyotes out of trouble. I still have live-traps out but dog does most of work.
A dog that kills poultry is like a garden tool that kills your tomato plants, learn how to use tool properly.
It does not always require starting from puppy since even an adult proven chicken killer can be brought into line. You could get immediate raccoon control even with a serial chickien killing dog if it is confined such that it denies raccoon access. Then break dog of being threat to birds which can be done without degrading effectiveness against coons.
Most important point to make is you likely intend have chickens in forseeable future. So if future coons are predicted a dog is a logical consideration. Agreed dogs not suitable for all parties owing to cost of upkeep. Upkeep cost is part of my reasoning for having dog serve multiple roles which includes hunting small game.
With poison applications, it is easy to get sloppy and take out animals not intended as targets.