I think Channel Blend is a more complex Color Balance.
You’re probably right. I’ll repeat what I wrote previously.
In all honesty, I can’t imagine using this filter except for those color space conversions in which the coefficients have been mathematically determined.
Use of the Channel Blend filter for these conversions makes sense. However, use of the filter for doing color corrections makes no sense at all, to me at least. Vegas has so many other tools that are so much easier to use (and understand) where you can immediately see the effects of the changes you make. In particular, I like to use Color Curves. It’s probably the one tool I use most often for color grading.
If you do discover something useful, please share.
wwaag