According to some, there is nothing wrong with FS if you read responses here including Gary's experience at the shop and that's a pretty broad swath. So it maybe like any front fork shock common on any mtb...owner experiences vary greatly in terms of positive versus negative experiences with off road air and oil filled shocks. Issues abound but they are the exception and not the rule after many years of off road front shock design evolution and of course rear shock technology on dual shock bikes has improved dramatically.

Any issues with the FS may even become sorted over time. One thing for sure about it if listening to reports, the FS is 'very set up sensitive' The little screws in the top have to properly adjusted. But like any product including press fit bottom brackets, there is a sequence and proper steps to adhere to and maybe its people working on their bikes and getting it wrong more than a design flaw.
There have also been reports on the new Roubaix, of Praxis crank creaking due to the crank itself and not the bottom bracket and some with a creaky seat post due to the way the seat post is attached to the frame.

Of course, there are reports of issues with many bikes. Designs aren't perfect, vary in production tolerances and no two bikes encounter the same riding environment, rider weight and power varies etc.

An arguable point, is, the design is a bit crappy. Honestly I am not a fan of the design and how to set up headset tension. The design to me is precarious and why some get it wrong that may not be the most mechanically inclined...2mm allen screws that if set too tight can bind FS bearings...and of course both tension and torque variance across the head set which puts an asymmetric load on the FS and propensity to bind or rattle if torque not uniform. So I believe the design is a bit crappy. Maybe not horrible, but over the top fiddly to set up.

So I believe a lot of issues with the FS first design and therefore setup related...preload too tight which is a subjective adjustment and adjusted with two screws which is an opportunity for asymmetric tension can bind the bearings and too loose a preload aka common steerer rock and headset 'chuckle' can occur of course which maybe basis for reports of a rattle. As it turns out to again use press fit bottom brackets as an analogy, design robustness can relate to set up sensitivity and why a subset of owners struggle. So I believe the design a bit weak due to sensitivity of proper preload which conventional bikes don't have as most when preload is adjusted a bit tight, there is no shock to bind of course.

FS installation: