Im not denying that BB tanks can thrive. Im say that DSB can add to the filtration, and I always want more filtration then less. Also how can you say there is no advantage to a DSB, If you have an heavy bio load you need all the filtration you can get. A BB adds no additional filtration, unless you are saying that DBS adds to the bio load instead of helping it?
Your key word...."can add to filtration", but my point is you can't prove it does vs a SSB or a BB. Without a DSB properly constructed by methods you've mentioned or maintained they provide no extra benefit and over time not properly maintained will become a problem. That is fact!!
A heavy bio load and DSB have no bearing or relation to each other. I guarantee with a good skimmer, flow and good maintenance routine a DSB wouldn't be needed!!!!!