My X4 failed during a live performance
got it back a few weeks ago under warranty and so far everything is working well. Had the X2 before that, never had any issues. I've not had any issues with the foot switches, seems they did a better job with the loopers than a previous multi effect I once had years back, where the foot switches had enough slop in them to bind up in the fully depressed position.
I've heard locally there's been a few bad X2's when TC first released them. My X4 I traded up to the moment they hit the shelves, but I didn't use it much having to work on a few songs with friends for a performance, then my Chimaera showed up, so the X4 sat on the shelf for a while. Afterwards, it took a while for the failure to show up. Turned out to be a bad board.
Was an intermittent failure to record, and the last effect "hold" would not perform the correct effect.
Awesome idea above about letting the effect run overnight. Bad boards can happen to any manufacturer. What happened to mine was not a design issue, otherwise I would not keep it.