The reason why DSB is not so common for display tank is it gets ugly over time! LOL... the algae on the sand, the glass put people off. As for tank crashing, it will happen if too much of the nitrate trapped under the DSB is suddenly released (i.e. suddenly rescape the whole tank, disturb the DSB). The recommended action is to get snails, starfish, sand dollars etc to turn the sand gradually. Also, you can turn some of the sand manually.