What does SelectiveBasePassOutputs (new in 4.11) actually do? When would you use it vs not use it?

4.11 added a new feature: “SelectiveBasePassOutputs” (listed under Project Settings: Rendering: Optimizations: Selectively output to the GBuffer rendertargets)

What does it actually do? For one thing I’m getting some lighting bugs with it (Lighting messed up in UE 4.11.2 when setting "SelectiveBasePassOutputs" - UE4 AnswerHub), but I’m wondering what the caveats are of when you would use it vs not use it?

In the code it all seems to be around rendering velocities. A lot of the code has checks for whether the lighting is completely static or not, and I think there must be a bug in one of them that is causing my lighting issue.

I have it turned off now to work around it, but I’m wondering what I’m missing out on?

I have also a bug that causes movable objects that are behind static objects to bleed their motion vectors for static objects. This causes nasty bugs with TAA and motion blur. Feature just seems to be broken.