I wear knee braces on the motocross track and occasionally when off-road. I’m very concerned with all-day comfort as much as protection. But being distracted or annoyed by protective equipment seems to cause more problems that it cures.
That said I was really impressed with the comfort of the Fluid Tech. The S/M/L size fit my normally between the smaller and larger sized knee brace sizing just fine and was not too small or tight in the knee and I could see how it could easily be padded up for less wide knees. Once adjusted the clip-in straps are a hit and make putting them on so much less of a pain. The full protection of the knee cup was as good as any and one of the best things about the newer knee braces.
How good are they? Well on a couple of occasions I forgot I was wearing them and that is the best thing you can say about a knee brace till you need it.