Been working on this today and I believe I have fixed some, but not all, problems with lighting. The problem in efenigma's video should be fixed. The problem sBarz was having with Retro Vertex Lit might still be there.
Forward+ lighting should generally be more stable, but I fear I might not be able to get the Retro Vertex Lit shader on par with the regular Retro Lit shader because of the way the shader needs to poll the additional lights. I don't know if it's even possible to do what I want to do only in the vertex shader, but I'll keep experimenting.
Either way, I'm uploading an update as we speak. Hopefully that fixes some of the issues!