We need someone who has used the new battery for 1D X (LP-E4N) in a 1DsIII, 1DIII or 1DIV and can tell if it had a longer life compared to the LP-E4.
That wouldn't be a directly useful comparison: the LP-E4N is advertised as having an additional 150 mA·h capacity over the LP-E4, while the capacity for the LP-E6 and E6N is advertised at 1800 mA·h.
You're right, and it practically makes this thread irrelevant. It seems the only difference in LP-E6 and LP-E6N is in charging setup as per regulation changes. I wonder where this titbit came from?
Haven't seen this discussed yet, but wondering if the 5D MK III will be able to take the LP-E6N. Seems the only difference is the LP-E6N has 200mA more juice, and I am suspecting Canon looks at the battery in firmware, but wondering if in the future with a firmware upgrade, the 5DMK III will be able to take advantage of stronger and likely longer lasting batteries from the 7D MK II