That's an interesting pipe. Although David has called it a bowtie, when I look at it, what I see is an evolved variation of Wolfgang Becker's wasp shape taken to an organic extreme. The pinched waist and asymmetrical shank flare endows the pipe with an organic feel as opposed to a sculptural feel. The pipe seems more to have emerged rather than have been shaped.
In terms of scale, at 6 inches in length, it is a big pipe, especially compared to Becker's wasps which have a traditionally more compact scale of around 4 or so inches. It seems like it might feel somewhat heavy and ungainly, but I could be completely wrong about that. Weighing in at 80 grams, it absolutely is not a clencher. Personally, I'm not fond of pipes with lots of extra wood on them where the weight is a result of massing. I think the design idea is a winner, but scaled down could be stunning. Just my opinion.
David has made excellent use of the materials. The plateau on both bowl top and shank end is quite beautiful and rendered to dramatic effect. As others have written above, he has maximized both straight and birdseye grain.
I really like David. He is a lovely man and possesses the humility and talent to really go places. I think it says many positive things about the KC show that this pipe was awarded best in show. Kansas City seems to me like it is a champion of the North American aesthetic in a way that most carvers here might never have dreamed could be possible.