GREAT idea, weight smeight. I won't be riding without at least one drum anymore. SA Drum brakes are set and forget, ZERO adjustment, any weather round the world ready. My XL FDD has 21,000 miles, just one bearing change at 17,000. Toured 4,200 miles. It does need a very strong fork.
I also just got an old 1973 CCM 3 spd. Now half upgraded with an all new rear SA RD3 and Dyad rim. Absolutely fabulous. The 70 mm seems to actually grip better than the 90 mm.
Dutch bikes use them for a reason ....