OK so I have looked at the Adam Block videos on SPCC and I will be trying it soon - but I'm not crazy about using terms like "accurate" or "true". I guess the main thing is - if that is what's important to people - are you not going to adjust the colors at all after it finishes? In other words - if you are going after an aesthetic final result - won't you be prone to alter the colors for max impact in final processing? Any changes to saturation would lose accuracy. So this isn't so much a question about the tool itself - but how people intend to use it - and if "accuracy" is their main concern. If it is - you better not touch those dials.
A second point is that there is always a disconnect between the filter passbands and how the final image is presented. I use Sloan filters for R, G, B - and even though I haven't tried SPCC yet - I believe it does support Sloan filters and would make an "accurate" view of a galaxy. But there is no getting around that the Ha emission will show as green rather than red - because the Ha lands in the r' filter, which maps to green. This is an extreme case - but in general the passbands of the filters are very different, and the calibration process is just doing a sensible integration over the passbands with appropriate weighting. But that only achieves so much in terms of "accuracy"
One reason I have avoided PI over the years is that its usage was prone to making highly processed images, and galaxies were consistently shown with exaggerated colors that were disconnected from reality - such as bright purple in the outer stars. So if people use this tool and do stick with the colors - and galaxies to start to show more subtle color variations - I think that would be great. But the images are likely going to be a lot more subtle and less jazzy.
Much of what is being touted here is based on principles I have been promoting for 7 years, and before PCC was implemented in 2017. I think this is the first example I described publicly:
It was based on using APASS stars as references, integrating over passbands, and showing plots of the resulting linear fits. But I described it as "calibrated" colors rather than accurate. The colors of galaxies with Sloan filters mapped this way don't look right - but they are data driven - and only a stretch was applied to compress the dynamic range. For a globular cluster I show that calibrated colors help reveal the underlying astrophysics that normally gets processed away - the example here being the horizontal branch. It also allows good H-R diagrams. The goal for me has been data-driven, calibrated colors that were not chosen or altered by the imager.
If you look at my astrobin, most of the RGB images are calibrated in this way, so they can all be seen in the same color context. This is one thing Adam Block promotes - and I fully support it. But it requires you not to mess with the colors after calibrating.
The APASS star measurements are limited in accuracy so they aren't ideal for this procedure and the GAIA data are clearly superior. But I don't expect a major change in colors due to this improved accuracy and spectral detail because a lot of the variation averages out - and the elephant in the room is the disconnect of the filter passbands with how the colors get displayed.
I wouldn't make a big deal about white balancing based on average galaxies - particularly when imaging a nebula. All you can really do is calibrate the image and say what you used for white balancing. But "accuracy" is a little strange to use there.
Finally - how will people use this tool when imaging the Fireworks galaxy? Will it rebalance the whole scene to remove reddening from the galaxy - while making the foreground stars overall bluer? Or will the whole galaxy be fairly orange? I'll be interested to see how people show that one - and if they adjust colors.