What have you had good success with before?
IMO, do that.
If you have found success with a method, why not do the same? As is evident here, even people with a plenum can have drool-worthy tanks. :thumbsup:
If you haven't had success, what methods? Your take on why?
IMO, different methods are suited to different reefkeepers, their livestock, and their practices/equipment.
While a DSB might not be aesthetically a bummer to lose space - if you've had success, good growth, and nice colored corals with it before - I'd rather look at that than 4" more of not as nice tank/coral.