I attended Ken's class on basic blacksmithing a couple of summers ago. It included an in-depth discussion of what makes a hammer work well. I learned several things:
1) How to swing a hammer better than ever before. Heck, it continuously amazes me how quickly wood splits with a hatchet now, or how quickly 16p nails get driven with an 8 ounce hammer. Nothing really new here, just physics. just the other night, I hammered some old u-bolt 3/4 inch thick into a leaf.
2) a definition of "balanced" for me: I watched ken idly tapping his hammer on an anvil when he was talking about something else. I noticed that no matter what angle he struck with the hammer, it always bounced straight back up. Its what made me choose to buy his hammer. (that and the discount from taking his class.) Later that day, I watched from the other end of the room him bouncing the hammer on the anvil, and how the hammer would fly up next to his head: without his hand on it. He just plucked it out of the air.
3) Hammering, like child-rearing, is more about what works, rather than which theory is correct.
4) The question about whether Hofi can back up his assertions with science: I think it may be enough he could hammer without pain. Ken noticed the difference right away. Do we really need studies by guys in lab-coats? I am a bit biased too. Master blacksmith...me nothing: I do what he says.
5) This is the first actual hammering method I learned. There are clearly other ones out there, and in future classes when hammering styles are a topic of discussion, I will give them a fair shake too.
Ken, thanks for your words. Not only inspiring, but it re-asserted a couple things you touched on in your class that I had forgotten. :)
--jason