If the light projected by a lens designed specifically for digital cameras, works differently to one designed for 35 mm cameras, then I would expect to see a significant performance difference between them when attached to the "wrong" camera.
My little experience suggests that it's pretty small. The major difference is the smaller usable image size, enabling DC specific lenses to be made smaller.
However the problem in lens design is, I think, that the 35mm film plane is flat whereas a digital sensor is not!
Carrying out a search in Netscape for Designing Digital Lenses gave http://www.megapixel.net/html/articles/article-43.html which is an article with some valuable ideas and diagrams.
Howard
