Honestly, only the Pro vs 1X sales would really give somewhat accurate insight on the case, because the price alone doesn't do the justice looking at previous generations - the PS3 was 100$ more expensive than X360, but most of that price went into expensive BD, XDR RAM and CELL BE. that didn't provide much/anything extra for the end user, and if anything, it performed worse,
Then the XB1 was 100$ more expensive than PS4, and it's not a secret all of that additional cost went into forced Kinect, so again, it also didn't provide anything more for the end consumer, and at the same time was also the worse performing system.
PS4 Pro and X1X on the other hand, now those machines did put all of their productions cost strictly into performance parts, so as oppose to previous cases, that extra 100$ for X1X does translate into better performance across the board, and it was marketed as such, as the most powerful console in the world, MS kept emphasize that, the reviewers also widely kept saying over and over than the X1X version of XYZ game is the best, and again, MS kept using those reviews in many of the accolade trailers and other marketing materials.
But how much of an impact did it have on the actual sales? Only MS has the data, which still, doesn't really give that accurate results, as both Pro and 1X were mid-gen refreshes, and many people already had an XB1 or PS4 console and didn't want/need to upgrade, let alone completely switch platforms once they already had all their current-gen library tied to the other.
So with all that being said, I would really like to see the scenario with let's say 399$ XBS, 449$ PS5 and 499$ XBX, just for the social experiment point of view ;P