Regarding MLU, what I find most annoying in the Canon 1 series is not that there is no dedicated button for the function, but rather that self-timer doesn't automatically combine with mirror prefire, requiring you to activate/desactivate both, and in the process incur the inconvenience of a lack of easy MLU access.
True, for uses for which precise timing is important, MLU cannot be replaced by mirror-prefire.
However, for all other uses, mirror prefire is vastly more practical, because it does not require the use of a cable release - DLSRs all use electronic releases that are quite bulky.
Typically, if you do a mix of tripod and hand-held work (as in travel photography) its very convenient to be able to just switch to self-timer mode with mirror prefire when the camera is on the tripod, and out of it when the camera is hand-held. If you used MLU, you'd have to constantly attach and remove the cable release when switching from tripod to hand-held.
Back in the 90s, when I was a Nikon user, one of main gripes against Nikon bodies was that they did not support mirror prefire. Bodies other than F series did not have MLU. My first Canon body, the EOS A2/5 had mirror prefire whenever the self-timer was activated (I think it was a custom function). This was a major improvement.
So why did Canon remove this feature from the 1 series ? It's not that a new button is necessary, probably no more than a few lines of code. Moreover, I see absolutely zero drawback on always associating self-timer and mirror pre-fire, so why not make it the default option ? Don't you think that any lobbying efforts towards Canon should be directed there first, because it is probably such an easy change to implement ?
As to Nikon, they clearly have learned a lot from Canon in a decade (IS, USM, aperture setting by dial, Af start button,...), but still no mirror pre-fire option at all ?
As a side note, despite the new "My Menu" in the mark 3 bodies, I find that MLU actually requires just as many button clicks than on the mark 2 bodies, so no progress there. The mark 2 bodies memorize where you were in the menu, so if all you used in the menu was MLU, you could access it as fast. On the mark 3, live view provides a one-click access to MLU, but because of increase battery use and possible sensor heating, I am reluctant to use it. Besides, it is still not as convenient as mirror-prefire automatically associated to the self-timer.
