... The gradual introduction allows them to spot any issues that were missed in beta tests. ... I prefer it that way, it gives me a bit of a cushion to see if anything nasty happens. I certainly would not install new firmware just before a big shoot. Thats asking for trouble.
For any firmware or software I update, I keep up to two previous versions on file, so I can revert back to an older version if I experience any problems with the latest release. I've rarely had to backtrack, but its good insurance to have, if for nothing else than peace of mind.
If the new 5D3 firmware were available today, I'd download and install it, regardless of my big shoot this week. I have the installer for the current (1.1.3) version on my PC, so I could revert to it, if necessary. Before I did that, however, I would switch to my back-up camera body if I ran into any trouble.
I completely respect the preferences of some to wait a while before installing an update, but they shouldn't press their conservatism on the rest of us. Personally, I would willingly become an unofficial beta tester, just to be able to put the promised new features through their paces.