questions about rmh testing and performance

My question is if there are any differences in the overall efficiency of any given combustion chamber/heat riser's design between when it has no mass and when the same stove has mass installed. I am hoping to be installing one this year and would like to know if anyone has noticed any difference in the strength in the draw specifically between an un-massed and a massed stove. I have gathered that most people test their appliance before doing all of the work of installing the mass and there might be some useful data to gather especially if it meant that adjustments could be made to increase overall efficiency.