I've owned 4 Rev Cs and still own 3 Rev Cs and a modified Rev C with 6 power tubes... aka prototype Rev C Triple Recto, and I've played 2 other Rev Cs. None of the ones I've owned/played are less gained compared to any other Recto version. Quite the opposite. You do need to use the right preamp tubes in these amps, Chinese12AX7C5 square getter, and properly selected.
I agree 100% with the MKIII + Rev F comparison. Less fizz, yep. The Rev C red channel modern is tighter, brighter, and way more cutting than any other Recto. Even vs the newest gen multi-watt Rectos. The main reason Mesa changed the original Rev C was to make it sound more different from the Mark series, cut the gain and change the feel of the amp. Maybe to be more like a SLO, who knows. But a Rev C and a Rev G red channel modern, will sound like completely different amps if the listener is blind-folded.
When I think organic and raw I think late 60s Marshall SLP 100W.