So I fiddled around with it in BeerSmith and Hopville's Beer Calculus, and adding a pound of sugar, be it dextrose, sucrose, or turbinado, only increases both the OG and the FG. What gives!?
BeerSmith says for 4# DME, 3# Vienna, 1# Dextrose: OG 1.060, FG 1.017
Hopville says OG 1.053, FG 1.016...