I recently got a few sets of the FSX 4-color and I really like them - they’re among my favorite cards out of the 15+ different varieties I’ve tried. The card stock is a nice, bright white, the ink of the 4 colors is very strong and easy to see, and the design of the court cards is my favorite of any brand I’ve used.
There is no denying these cards are very stiff. I think they shuffle well if you’re willing to put some muscle into it, but I can understand they wouldn’t be for everyone. If you’re doing the “dealer riffle shuffle” where the cards stay face down, it’s really not a problem. It’s when you do the classic “grandma” shuffle that the stiffness rears its head. The stiffness can also mean less experienced shufflers will have a few card explosions throughout the night. They do break in and start shuffling better after a few hours of use.
Just this last Friday I hosted a 6-hour cash game with 7 people and introduced these to the guys for the first time. One person did NOT like them at first because of the stiffness, but got accustomed to it throughout the night. Another regular player disliked the 4-color aspect, but that’s just a preference thing and he can deal with it since I’m hosting.

. Everyone else was indifferent.
There are several other card stocks that I prefer shuffling over these FSX cards; however, for me the premium look and feel when not shuffling is outstanding. Since I’m only shuffling one out of every 6-9 hands in a game, these cards are worth using for me and I plan to keep using them as my main cash game cards.