3ds max has come a long way in previsualization in viewport.
Great job so far!.
That said, why not go all the way with support for volumetrics, SSS and incorporating the full customizations of Arnold lights, properties and modifiers:
-We should be able to see the effect of including and excluding lights on objects in the viewport
-decay and light blockers as well.
If these are implemented, with all the improvements so far, there would be far less reasons to do production render in Arnold, rather than viewport.
