Most would do the DSB in the Fuge, but if its not big enough, its not really going to be able to a good enough job. If you plan on a DSB I'd recommend doing it in both the DT and the fuge.
I personally don't care much for them, they require to much care per say, and after a certain period of time, you have to change it the sand out.
Barebottom. For maintenance purposes, it is easier to just use Live Rock and Macro Algae for your fuge. When you have to clean detritus, just shop vac the bottom of the fuge and clean it. Sand is a pain for a fuge. This is where most of your detritus gets trapped and you will have to gravel vac it.
Keep it simple. I am growing both SPS and LPS crazy.
I ended up taking the sand out of my fuge. It looked cool but turned into a detritus trap. Once I got the sand out I was able to increase circulation and tumble my chateo and it's exploded. Now my fuge is super clean, only live rock and macro algae.