BTW, regarding the menus disappearing quickly in LiveView, there is an old post (10/24/12) by A1ex on the subject of AF Confirm Chips, on cameras with newer than Digic4, where the menus were closing quickly. (Grasping at straws here, but I thought I'd mention it in case there is a hint of a clue in there somewhere.)
About 10th post on page 1/1:
http://www.magiclantern.fm/forum/index.php?topic=3312.0
To be clear, I'm not saying that the presence / absence of the electrical contacts causes it. (In fact, on my 6D, the timeout is the same 6 seconds whether a lens has the contacts or not). But if the 5D3's AF logic was sending some signal one to two seconds (after the menu button press), maybe there is something in the 6D sending a signal 6 seconds after the last button press. (What waits 6 seconds in the 6D, I wonder.)
Also, although repeatedly pressing the Q button will NOT delay the timeout at all, spinning the back control wheel will delay it indefinitely, until about 6 seconds after you stop.
About 10th post on page 1/1:
http://www.magiclantern.fm/forum/index.php?topic=3312.0
To be clear, I'm not saying that the presence / absence of the electrical contacts causes it. (In fact, on my 6D, the timeout is the same 6 seconds whether a lens has the contacts or not). But if the 5D3's AF logic was sending some signal one to two seconds (after the menu button press), maybe there is something in the 6D sending a signal 6 seconds after the last button press. (What waits 6 seconds in the 6D, I wonder.)
Also, although repeatedly pressing the Q button will NOT delay the timeout at all, spinning the back control wheel will delay it indefinitely, until about 6 seconds after you stop.