Hey, this does look great!
Since this is a different method than 3dgs uses for it's shadows, if the camera was moved in between the light source and the shadow, it would not get weird results?
Doesn't the fps drop or something? I mean, I have no idea about all this, to be honest, never done anything like it. But what you say up there... rendering the view twice etc... sounds like it would take quite some time...

Good luck with this!