XM-L2 is the way to go. About 20% more efficient.
Yes, we know it because of the datasheet.

(More pictures here)
There are several places who sell various 5B tints, intl-outdoor seems to be the only place who have a T4 and in 80 CRI Minimum version at the moment.
I can not say that what you have seen is not a true.
According to my eyes and the ansiwhite picture NW 80+CRI B/C tint will be more yellow than NW 75CRI A/D tint. A/D tints I perceive as more pink/rosy/red. From trustworthy vendors I find the tint to match the ansiwhite picture very well.
Can you come with one or several specific examples of what you say. Precisely which emitters, and where they are bought from?