The 68mm works fine but gives no extra power over the 65mm and also felt a little less responsive in my application.
Cheers; does the 65mm require any adapting to fit? At least with the software, if i do step up to the 68mm (for SCing) then it is only a tweak of parameters.
straight swap with a 58mm TB and a very good mod - but you will need the Dutch SW to make it work