All the Trochus species should be fine without sand, and most of the nerites should do well. A few species do burrow in sand, but they could probably live without it.
There are several species of Nassarius that are perfectly content to nestle into the algae rather than burying themselves, but most need a sand bed. The rule of thumb for which Nassarius species need sand goes like this: if the shell is glossy, and has no algal growth on it, it's a sand dweller; if the shell is not glossy, and has algae growing on it or a lot of encrustations, it can do without the sand bed.
This rule pretty much applies to the ceriths as well. The cerith species that you see a lot in the hobby (the ones that look like they are grey with black specks on them) aren't really sand dwellers, and may be collected by the hundreds off of intertidal rocks. There are some others that are truly sand dwellers, and these usually have clean, unencrusted shells, except that the spires may be somewhat encrusted or discolored. The prettier the shells are, the more likely they'll need a sand bed.
Hope this helps a little. Cheers,
Don