The flip side of the coin is that a majority of experienced discus hobbyists & breeders on the simplydiscus.com forum have used bb white-bottomed tanks for years (usually painted on the underside, either that or with a thin layer of white or off-white sand on the tank bottom),.... as have Asian discus fish farm breeders & exporters for over 40 years in Singapore, Malaysia & Thailand- I know this because I spent several years living in Singapore in the 70's and visited a number of commercial discus exporting operations while there.
The upside to that is that it's so much easier to spot & pick up all debris in order to maintain quality water conditions for the discus.
I'll pit that against Dr. Weitzman's experience & commentary any time.
But hey, everyone has their opinion and views.
P.S. - Byron, have you seen Rick Grange's (Canadian Aqua Farms in Maple Ridge, B.C.) tank bottoms ?