My 2 cents - the U-Tail has declined in recent years due to the finese craze. I use a lot more straight tails than I do U-Tails - particularly the Swamp Crawler. While we're on the subject my favorite U-Tail of all time, hands down, was the Manns Manipulator. It was poured with the flat ribbon tail in a circular shape and you pinched off the connections to make the tail flow out behind. The body had good mass to it but you'd probably want it to be larger and longer.
My advice would be to concentrate on larger worms. I know it's a niche market but its what I see in my part of the country. You can always start big and scale back the size for rev2.
BTW - Zoom came out with a longer 7.5" version of hte Swamp Crawler this year... but not in the colors I want (yet).
