Thanks you all who participated in the discussion about mining system here and here. The discussion was effectively.
So we agree with opinion that realistic, smooth asteroids looks better and "sector system" is enough.
Also you remind to us that idea about salvaging of derelict space ships \ stations it almost the same as voxel asteroids, but more interesting due possible defence systems.
So we will improve current asteroids and implement derelict space objects.
Probably we will start some similar discussions later.