So...
IDK when this happened, but the 3D Ray-traced preview works in hammer 4.
I can't get the 3D lighting preview to work however There's a few downsides that I have noticed.
1)It loads in another window and turns the 3D window Checkered. If you hover over the main application, the ray-trace preview will pop behind it. If you have 2 monitors, you're good but it's aggravating for anyone with limited screen space.
2)Update rate leaves something to be desired. And you can't navigate in the window itself, you need to manipulate the cameras in 2D.
3)Sky isn't rendered
4)Shaders aren't taken into effect: Water doesn't render, bumpmap layers are visible as a checkerboard, sky textures are rendered as the texture themselves.
But hey, It's something.