Buttons too close / Feet not secure
Functionally, the FS3X is a solid pedal and is an excellent addition to the RP360XP to extend its live performance capabilities.
My primary complaint is that the foot switches are too close together (2-1/4" center-to-center).
I wear men's US size 11 shoes, most of them with soles that are 4-3/4" wide, meaning that in order to press the center button without pressing one (or both!) of the side buttons, I have to angle my foot.
This seems an odd oversight on the part of DigiTech engineers, since the RP360XP buttons are more widely spaced (though still not generously, I have to say). This is not a deal-breaker, but it could be a show-stopper if you accidentally press more than one switch in a live show! ;-)
Another complaint: the adhesive rubber foot pads have already fallen off after less than two months of use. They should have been screwed into the metal case instead of relying on adhesive. The painted metal bottom surface makes it pretty slippery, so I'm forced to replace them for the unit to be usable. Again, not a huge deal, but it seems another oversight by DigiTech's designers. (The RP360XP's rubber feet are starting to fall off, as well. [Sigh])