I had a DSB for 2 years and never had any of the problems that many say you can have, no major algae problems, no HUGE nutrient trap. When I took it out the sand was almost all very clean.
That being said my
250 is BB and I will never go back! After a while the whole bottom is coverd with coraline, and since I used starboard (actually cuttingboard) the zoos have almost covered the whole bottom.
Pros:
-less expensive
-more room for water
-allows more flow which keeps detritus in suspension
-no critters to buy again and again
-things like OM 4-way don't get clogged
-no sand storms
cons:
-some animals need sand
-nassarius snails are cool
IMO sand only looks good for a little while, and then it never looks great. Nobody that has come over to my house has mentioned the lack of sand. My corals (mostly SPS) are all growing like mad. In fact my very first coral (probably first 10) were all SPS and I didn't find them hard or finicky at all.