Joined: Jan 2009
Posts: 44,172
Likes: 6,404
From: New York, NY, and High Falls, NY, USA
Bikes: 1962 Rudge Sports, 1971 Raleigh Super Course, 1971 Raleigh Pro Track, 1974 Raleigh International, 1975 Viscount Fixie, 1982 McLean, 1996 Lemond (Ti), 2002 Burley Zydeco tandem
It would make an interesting experiment. Disc brakes are getting great reviews, but as [MENTION=73614]rhm[/MENTION] says, the frame has to be ready to accept them. They don't weigh much more than rim brakes.
One possible compromise is using a drum brake in front and a rim brake in the rear. The rear brake isn't that important anyway, and you save a little weight that way. Sturmey Archer makes a front hub that has both a dynamo and a drum brake.