The M with autoiso and ec is available in the 1D4
we are talking about the 5D 3 and a possible FW Update for it. So forget your stupid 1D 4 for a while and its totally awkward scratch-yourself-on-the-back-of-your-head implementation of pseudo Auto-ISO.
The 5D III and any other Canon EOS camera needs a firmware with a full and unfettered implementation of Auto-ISO.
* user-settable upper and lower limits for 1.) ISO 2.) shutter time and 3.) aperture - to be used as required in various exposure modes [Auto], P, Av, Tv, M
* plus regular operation of exposure correction in M with Auto-ISO on
... anything less is unacceptable and total crap.
oh ... and just to make sure: we want it NOW and we do NOT want it hidden away under unlabeled custom functions 91,92 to 99 plus safety shift enabled and CTRL-ALT-DELETE-DIRECT-PRINT-button pressed simultaneously ... oh no, we want it readily and easily accessible!