I don't think you need seperate models. I think if you need seperate models then the first one wasn't designed or built very well.

Quique's Euphoria excels at both the Prelim and Finals Patterns.

If you really want to give some credit for the Bipe go back to 1989 with Tony Frackowiack and Ken Bohnemen(sp?) and the Fig Leaf.

Designing a building a Bipe is tough. Especially to get one good enough to Win the World's. I think Quique crossed that bridge the first time.