I just started testing this, it'll take a while to complete however:
The nested Best project takes around 1 second per frame to render.
The main project set to Good renders frames per second.
Which is how I'm hoping it'd work. I'm nesting a 3D graphics veg for the titles which needs Best. The rest of the project is vanilla DV that doesn't need Best. If I've got to render the whole project at Best just for the titles that kind of defeats the usefullness of nesting.
OK,
just tested this. Renderer out the first 24 seconds of the project at Best and Good.
The titles are identical regardless of the render setting. In other words the nested project is rendering at it's project settings, not the render settings.
Rendering at Best slows down the rendering of both the nested veg and the main/parent veg. That kind of makes sense if the nested veg is delivery uncomp frames to the parent. Whole 23 seconds took 4:52 to render.
Rendering at Good the whole test segment took 4:21.
Doesn't seem like much but all that saving was in the few seconds of vanilla DV and for the whole show there's a lot of that!