Rich, I found this on FM:
"Taking measurements from the photos on the Japanese website, it would appear that the lens is approximately the same size as the current EF 500 f4. Length 15 inches, diameter 5.8 inches. Assuming a similar weight of 8.5 to 9 lbs. this will be a considerable chunk of metal and glass.".
Your right about hand holding it, it should come with a gym membership, haha. Should be a sweet birding lens.