Dear color scientists,
I am thinking and searching about this, but haven't found a sufficient answer. As far as I understand it, even a slightly wider gamut, like sgamut3cine should give no benefit to just shooting in 709 in the first place, since the out of gamut tones must be compressed anyway and rather effect, depending on the compression process, the tones that are already in 709, like skin tones.
If shooting in wide gamut, theoretically the colorist could work with the extra gradation in the out of gamut tones of a wider gamut, but for any given color depth, there will be less data values for the tones that are already in 709, if the distribution of values is equal.
On the other hand, if you set, a Sony camera for example, to 709 gamut, what is it doing internally? The native gamut of the sensor is much wider. Would it make any difference of doing the compression in post? I couldn't see a difference in a quick test with the c300II.
When people talk about this issue, they connect log and wide gamut in one sentence to explain larger dynamic range, like they want to hide not knowing the details. Log-recording is data value distribution to output-values of brightness levels not saturation.
Would be grateful for some clarity. I feel I am missing something.