Give me the lock every time. Particularly when working with two bodies, the 5DI or II, without the lock, hanging at your side either with the standard strap or a Black Rapid, the mode dial often gets easily bumped.
On my old 5D I had to tape the mode dial onto the chosen setting. Not a good look. Working fast and in the zone on commissioned jobs I have lost shots due to the dial being bumped.
Thank you Canon, this is what the user feedback requested, and you have delivered.