Just a quick update - infinite far plane projection is implemented in all the render systems now, and coupled with the vertex program extrusion I have found it’s made a big difference to the robustness of the volumes - degenerate cases (objects passing too close to the light, etc) are now a thing of the past I think. The engine automatically enables infinite far plane projection on cameras when you use either of the stencil shadow techniques, and vertex programs are available to extrude them.
The only thing stopping me from committing this is that I have one last annoying bug to track down - when using hardware exrusion I get a corruption on the light cap of SubEntities other than the first when in zfail. I’ve at least narrowed it down to that case, so perhaps after a good nights sleep I’ll see where it is. Once I squash this I can put this pretty sizeable change to bed.