I could say a lot about the "Dr. Ron DSB Theory", but it wouldn't be cool to say it. I have used DSB's with good results, but I don't care to use one again.
I think it is ok to talk about Dr Ron's theories, but its not cool to bash him.
My current thinking is treat a sand bed like any other filter - in other words you need to clean it periodically either by changing it out completely, vacuuming it, or storming it regularly. The idea that you can leave it alone forever is a crap shoot.
I also agree that a smaller sand bed would be more manageable, and would take up less of the valuable real estate in our tanks.
I think that in theory the DSB could be completely self-cleaning, but more detailed methodologies need to be documented in order to have a more universal implementation of it. Without that level of detail, its a crap shoot just like you said.
Just a personal preference thing I guess. I don't care for the look of the really deep bed and I don't like having all that fine sand in the display tank. I find it hard to get the flow I want without blowing the fine sand around. Basically, I didn't see any real benefits over when I was using a shallow bed or a BB and there was the downside of the annoying fine sand.
And FWIW... ...I know people talk a lot about dentrification in these sandbed discussions, but IME it's not been an issue at all. In the tanks I've run with live rock and skimmers, I've never had any detectable levels of nitrate regardless of whether I had a little bit of sand, a DSB or no sand at all. Some of those tanks were FOWLRs with heavy fish loads and very little maintenance (ie. water changes) being done too...
IMO the whole sandbed debate is sorta like the lighting thing. I don't think it really matters all that much how you do things as long as you accomplish the basic goal (nutrient export in this case). I say use whatever method you want. Each method has its ups/downs like everything in reefkeeping (and life )...