The author is actually very specific when it comes to ride quality:
"There’s a road near my house I regularly use to assess ride quality ... Like many in my locale, this particular road is covered in heaves, dips, potholes, craters...."
He is talking specifically about potholes and the like. And in this respect, it is totally believable. Plus, those are bypass shocks so they probably do well over small chop as well.
I have gone through 4 sets of front springs and 2 of rear springs and my current setup, while neither fancy, nor expensive will obliterate a stock non-Pro 4R on any offroad terrain or on any rough patches on paved roads. The bigger the bump or the deeper the hole, the bigger the difference. It is absolutely true that some of the things you notice stock, do not exist after an upgrade. Caveat: I did need the 650lb springs to achieve this, the 600lb were fantastic on road but too soft with the 6112 off road. But I have forgotten to notice, for example, coming off a curb. I realized that when I went down a sharp curb in a forum member's Eibach equipped 4R and it reminded me that curbs are a thing with a less stiff suspension. In addition, I no longer notice the lack of KDSS. There is no body roll in corners, there is no being pushed around like a toy by the wind on interstates, and I am not sure what more I can ask from a high center of gravity 4x4 on road. Small chop is noticed, yes, but that's a small price to pay since airing down solves that offroad and it is rarely an issue on road.
Since the Fox setup is internal bypass, it may be able to do very well over a variety of terrains, even small chop where mine is on the firm side. I will venture a guess that it is probably softer offroad than an aftermarket performance setup would be, but that's just a guess.
EDIT: and offroad, the stock non-Pro 4R is laughable compared to an upgraded one. I came from Subarus so initially did not notice but now I cannot believe I drove as much as I did stock. There is no comparison in the speeds and I am not talking racing but simply driving easy trails at twice the speed I could do stock due to bottoming out or even hitting skid plates and bumpers. Speeds over moderate rated trails in guides like those of Charlie Wells have improved a great deal as well. Rarely using the brakes and not taking forever on typical desert trails makes a HUGE difference.