It adds around a $1 per pound of meat if you are selling it. Is it worth it? Hell yes... at least for me.
It's very time consuming, hard and smelly work. Should everyone learn to do it? Yes. But if you are doing batches of 20 or more birds, the time you invest in equipment and hours makes the processing route reasonable. And if you are selling, then you will probably be required to use one anyhow so learn the system inside and out.
Also, if I'm charging top prices for high quality meat, I can't have hte birds looking like they've been through a blender. The processor simply does a better job than I can do. He's also far better with the kililng stroke than I am. They're dispatched before they even have a chance to be scared. I accept that and will continue to use a processor because they are more skilled than I am.