Firmware updated on my 1DSMK3 today - no issues.
Camera going in Tuesday for the focus adjustment - which Canon CPS service tell me is NOT dissasembling the camera - but rather plugging a computer into it to ensure its focusing exactly right and adjusting via software if required.
I already feel I get spot on focus - so will be interesting to see how it goes after 'adjustment'.
Canon Australia tell me it will take about an hour to test and adjust if required.
I will post results post 'adjustment' [if any is required].