Belt drive is going to be impacted more by variables like platter mass. My Sota has a fifteen pound platter and so once it overcomes inertia it is very stable at speed. A lighter platter would be more susceptible variations in engine speed, belt imperfections,etc. An inexpensive belt drive could very well be bested by a quality DD, but like anything else its all in the quality of the execution. Theoretically DD might have advantages, but it seems belts have won out by trial and error as the better solution.
Both types of tables do still use round wheels though.
Both types of tables do still use round wheels though.