I have been a bike technician for the better part of a year now after retiring from an engineering career and I see a lot of wheels in for repair and have researched this subject quite a bit since I am also a Clydesdale rider. I am in the process of building a bike as well.
I would not even consider seriously riding a wheelset with 20 to 30 spokes regardless of brand. It is just not smart. Depending on how you ride, your weight and where you ride you may get by with it for a while but why push your luck. You could have a serious accident from a wheel failure and trying to save a few grams, gain some minor aerodynamic advantage or have cool looking high tech wheelsets is not worth the risk for things that will make no difference in the longrun.
My lightest wheel set has 32 spokes and at 250# I consider this minimal. I just built a set using DT Swiss TK540 rims and Dura Ace hubs with 36 DT Swiss Comp Butted 2.0/1.8 spokes. I was going to use Mavic Open Pro rims but they took too long to deliver so I switched to the DT's.
If you go to http://www.prowheelbuilder.com/ to order wheels and enter your weight in the 250# area, most of the time it will not let you even pick less than 32 spokes except for the strongest rims and it is usually not recommended.
Edited by vjbknife - 10/31/10 at 8:30pm