GKnot basically started out life as a bitrate calculator. It is opensource so anyone can update it. AutoGK on the other hand is closed source and the developer isn't adding new features, just bug fixes mainly now. If you are happy with AutoGK's output, then I see no reason really to go further. For some people it is all about the encoding process though, not about watching the final product. I tend to avoid guides, so I really can't offer anyway. Plenty of info around if you are willing to spend the time to look.