Set 3 or 4 Dog Proof traps 6 feet apart and bait them identically. It is highly likely that you may catch a coon in every DP trap. At least the first day or two. So that is proof that trapping and destroying offending raccoons in fact protects your pet chickens.I agree with you. They learn to avoid the box traps.
Also, relocating the invasive raccoon only delivers your problem to someone else.
Most of the time, if the culprits aren't moved far enough, they'll be back. Raccoons have huge territories and may know the direct route back to your place.
Moved far enough, relocation causes it to compete with existing wildlife in the new territory in an environment it doesn't know and may not be able to find food or water. That isn't necessarily humane. There will often be fights with those already in that territory resulting in death or injury at best. In most places, relocating is not legal because of the possibility of introducing disease into wild populations.
As for the leg trap, they don't maim and are removable. They are also much more effective and much less expensive than a box trap.
I can buy 5-10 dog proof leg traps for the price of a good cage trap.
http://www.flemingoutdoors.com/dog-proof-raccoon-traps.html