Say, I have been using my R with a 2.0tc vii with my 100-400 vII. I don't want to buy the Rf mount 2.0 tc as I don't have any R lenses. What I am wondering is if I will see a AF difference if I upgrade to a 2.0 tc VIII over my vII? I know IQ is better using the VIII, but just curious is the AF has any type of benefit. Not really sure if anyone has this issue, so thought I'd throw it out there.