I agree with spot... in court you couldn't prove those dogs killed your birds, just that they were on the property and were eating them. Can't say a coon, possum, hawk, human didn't kill them and the dogs hearing the fuss came over to investigate.
If you were concerned about your neighbor keeping their dogs in you'd have called animal control/the police. Since you haven't done that you are accepting that it's gonna happen, and that it's your job to lock in your flock against ALL predators climbers or canine. Least I can hear a lawyer making those two points. *rants about legal system*
That's somewhat the way I look at it, why I built my coop the way I did and why our property is fenced to boot. But, I'd also shoot a dog I saw hurting my pets, or call it in for the Pros to deal with. If I let my hens out At Large, able to get anywhere on my property or someone else's, then I can only blame myself if their being out gets them killed. You have a chicken yard, and while it may keep the hens in, it clearly doesn't keep predators out. So, while it protects your neighbors from your pets destroying their property it doesn't protect your pets from any animal threat. Keeps you from being sued for damages against others, but doesn't prevent damages against you.
Since the guy is offering, I'd ask for HALF the costs of POL (if you can find them) or as others have said chick +food per day x#days old.
If a neighbor's dog gave mine rabies I wouldn't sue because I neglected to get them vaccinated against it. I'd accept that both our dogs are lost and try and move on. In the end, a neighbor's pets are his responsibility but then, so are mine.
Because of that I'd take half the responsibility, just to keep my neighbor friendly. With the stipulation of course that if it happens again I'd make the call about the killer dogs and expect full reimbursement. EVERYONE makes mistakes, including me, so trying to pin all the responsibility for my pet's whereabouts on someone else doesn't sit well with me.
So, POL x # plus shipping divided by two would do for me. And, rather than restocking I'd prolly put that money to use for better security so what's left of my flock is safe, THEN rebuild the stock. *passes salt cellar*