In any event, the histogram shows the values in the rendered file, but does not indicate clipping in the raw file. This could cause problems when one is judging ETTR exposures.
Although the thread's topic originally was more about sharpening before it turned into Guy bashing, you step-wedge images show the issues with tonecurve rendering in PV2012 nicely. The fact that highlights that are clipped in Raw do not show that in PV2012. In fact, it does an automatic highlight recovery and, IMHO more importantly, a default highlight compression. That latter fact is exactly what Guy Gowan was harping on about.
As we can see in the attached chart I made from your Stouffer stepwedge conversions, and compare the PV2010 and PV2012 with the original step-wedge data, it is clear that the default PV2012 conversion suffers from significant upper midtone and highlight compression. That would indeed be detrimental for bride's dress and white cloud image content. The PV2010 conversion is much closer to how the original data (the blue line in my chart) would look in a straight conversion.
Of course Guy Gowan doesn't mention that the Highlights and Whites controls in PV2012 can help to restore highlight tonality, because that doesn't suit his agenda, but he does have a point that one would need to work the highlights in PV2012 conversion much more than usual, and similarly the shadows in a PV2010 conversion (which is what he advocates).
All this demonstrates that there is a bit of truth in all positions that are defended and that PV2012 can create a good image, with recovered highlights, but one really needs to work the PV2012 files very differently. One should e.g. not apply an simple S-curve or Clarity to a regular PV2012 conversion to boost overall contrast, if you want to keep some life in the highlight rendering. Work the highlights if you want the images to sparkle, and apply a curve adjustment if necessary.