I agree completely with the Crushed Coral issue. I used to use it back in the early 90's, but at that time I had it covering several large undergravel filters which were powered with multiple powerheads to create a nice water, hence O2, flow through the coral. However, I am sure there remained anaerobic spots anyway. That type of system (crushed coral with powered undergravel filters), actually works quite well, but is antiquated and neccesitates increased hardware in the tank itself.
In addition, to the biological benefits of a DSB the aquarium inhabitants seem to like the sand much more too! Especially any fish that burrows by nature, e.g. gobies, and the various critters that forage off the sea floor, e.g. crabs, shrimp, snails, etc.
Corax, All I am saying is not all system set-ups are neither ideal or practical for all situations. It is my contention, based on my experience alone, that a good amount of H2O changes, good water cirulation, a DSB, and a Biowheel, have all served me well for my small (10 gal) Q-tank. Therefore, if it has worked well for me I am inclined to share my experience. I agree, for a larger tank I would not use biowheels becuase, as you have inferred there is likely no need provided you have enough LR.
Happy Holidays.
P.S. I can't wait until I post a question surrounding best recommended filtration as I begin set-up on my new 125g following the holidays. The trouble will be sifting through all the advise and deciding which way to go.
