have to admit, I'm a younger rider, and am sorta baffled by the idea of riding, let alone racing, on 20s.

I can weigh in on the question of wheels though, but pointing out that there are still some manufacturers making "traditional" looking, low profile wheels, Williams Wheels 19s: http://williamscycling.com/sys19/sys19.html

however, their more aero clinchers, the 30s, are still extremely light: http://williamscycling.com/sys30/sys30.html

Basically, I think these days due to new materials and whatnot, the aero advantages outweigh the weight disadvantage on so called all-arounder wheels, till a certain point that they only become useful on flatlands and in time trials