Thanks, Harlequin, for a fascinating post.
I am coming into this discussion rather late, but most of the previous responses have been re-hashing of stuff that appears over and over endlessly. I have myself tried to refute Starlight and Time, but it keeps rearing its ugly head, and no doubt will continue to do so.
Getting back to the original post, I have one confusion. You state '5.8 million years ago the orbits converged to almost the exact same orbit'. Now if the original body/conglomerate started to diffuse at this point, why didn't it start ten million years ago, or three thousand million? The major planets have been there a long time!
Alternatively, if the diffusion was caused by an impact, then the orbits should not converge on a particular orbit, because there would be a discontinuity in their orbits at this point. They should converge on a particular LOCATION, not a common ORBIT.
Was this just a bad choice of words, or is there something I do not understand?
Mike.