Andrew, sorry but you are totally wrong on the rec709 section of your MKIII review, it still is full range not 16 - 235, looking at Dan Chungs samples for example, with Avisynth they're clearly full luma.
[url=https://vimeo.com/38728208]https://vimeo.com/38728208[/url]
What has changed is the color matrix from BT601 to BT709 this only affects any conversions to RGB, like for preview and color processing, probably done because when users transcode they generally loose the BT601 color matrix reference, so before BT601 would have been incorrectly replaced with BT709 as BT709 is default for HD when nothing is declared in the header, as a result pinks would shift to orange, now that mis representation won't happen.
Also Canon MOVS are still flagged as 'full range' in the header of the h264, so any codec like QT immediately squeezes the luma 16 - 235 bringing it into the NLE to ensure it encapsulates the full range data, this is unnecessary for an NLE like CS5 to avoid the luma sqeeze the full range flag just needs switching off.
But if decoded with a codec that just decompresses without scaling luma, it's clear to see mkIII sources are still full luma.
Finally I'd suggest avoiding 5DToRGB well at least the beta, may be that's updated now, because the test I did with it recently with Canon MOVs showed that in fact 5DToRGB scales the luma 16-235 in transcodes to DNxHD for sure.
Only the color matrix has changed.
A link to a couple of test files to illustrate codec handling of Canon MOVs.
[url=http://www.yellowspace.webspace.virginmedia.com/fullrangetest.zip]http://www.yellowspace.webspace.virginmedia.com/fullrangetest.zip[/url]
And a link to a Canon MOV (T2i) illustrating what really is in a full range file where the flag has been switched off to see how a NLE handles them differently depending on flag on/off.. Personally I think that the Canon MOVs should be quickly remuxed and the flag switched off to avoid unnecessary luma squeezing.
[url=http://www.yellowspace.webspace.virginmedia.com/flagoff.mp4]http://www.yellowspace.webspace.virginmedia.com/flagoff.mp4[/url]
Due to the codecs honoring of the full range flag any transcoding with tools like Mpegstreamclip will also squeeze the luma.