I am going to answer the hand shock question from years of swinging hammers. I am not going to say that I have swung them all, but have swung many metal, man made "plastics", fiberglass and woods. There is no question in my mind, and in my aching aging arm that wood is more forgiving than any other material I have yet experienced. The balance is hands down better also. Take two 22oz framing hammers side by side, one with a wood handle, and one with anything else, and not only is the shock factor in favor of the wood, but so is what I will call the "power delivery."
Don't take my word for it. Go to an area where a new housing development is going up and take a stroll. You will see wood handles 10 to 1 over any other choice being used by the guys who use them every day.
Of coarse for total durability wood could indeed be second to the metals and other man mades. But a good wood handle can last many years if not abused.
IMHO