i have a dsb... about 3". sometimes it looks good, sometimes it doesn't. i would say, if you do get one, get as fine sand as you can. i have aragonite, and even that is a little big for my tastes.
however, it does help keep the nitrates down considerable. also allows you to have cooooool burrowy snails and sea stars.
to the naysayers who harp on it being a nitrate trap. well, a dsb is something that needs maintenance, just like EVERY other part of your tank. slowly changing it up is a good thing, and i mean, honestly, who among us doesn't do a tank overhaul once every 2-3 years? come onnnn.
that's the ideal time to swap the sand. just watch your params when you are doing maintenance on it, and be ready to do a water change if things get skewed when it's stirred up.
i love it. there's sand in nature, we're approximating nature. do it.