The way I understand 3d carving is that any time the x, y, and z axis are in interpolated motion together
you have 3d carving
I would be interested to see how that 255 grey scale deal comes out I know like in v-carve it uses grey scale to generate gcode for 3d carvings but it also as 4th axis support
that being said you could still produce the same result as the statue if you double side machined a piece