I personally still believe that the image of his son screaming/begging for help was so close in imagery to the haunting images of his premonitions of Padme dying that it was this point alone that reached Anakin.
He seemed quite happy all the way along that if Luke pooch screwed the deal then bye bye Luke.
Also, a lot of what GL has said about the OT has to looked at slightly differently now that all 3 PT movies are out. As this allows us to see Anakin and to learn him a little better
And Anakin did everything for and because of Padme. His fall to the dark side was because of her, so why not his choice to return to the light?
And no Ushgarak, I am not trying to get into an argument over canon. That is not the purpose of this thread, merely to see what tripped that switch in the brain to cause the death of Darth Vader and the rebirth of Anakin