Is the tank currently stocked, or is this a re-vamp?
The trouble with disturbing any sandbed, esp. a DSB is that there are compounds (such as hydrogen sulfide) in the anoxic layers that you do NOT want in your water column. If the tank is stocked, I'd do it a small section at a time by vacumming it out, run some extra new carbon, and do a partial WC. Once the tank settles down do another section in a couple of weeks.
Also remember that by removing the DSB, you'll be removing part of your biofiltation, so it's important to allow the tank to catch up.
I generally run 1"-2" of #3 or #1 grade aragonite sand, as it "lays down" much better than "sugar-fine", yet doesn't trap detritus like CC.
