Some people look at it like which technique do you prefer, I look at it like what animals do you wish to keep, and what do they need.
There are benefits from each way, BB shallow, or DSB.
If I were going heavy sps, where typically we do very heavy flow, 60x or greater, you're going to have a sandstorm for one, and two those tanks run pretty sterile, so a BB would be my choice.
I prefer a mixed reef, and I always have sand dwelling anemones, they are my favorite, but they require a DSB, so I go 4" or deeper(I'm at 5-6")
What many call tweeners seems to be where most have issues, not deep enough for denitrification beny's, just deep enough to hold a lot of junk it seems.
I think this is where many get confused or have issues w/ DSB's, that and stirring up DSB's.
That's why I say DSB's are great, but you need to do it properly if you choose that route.