I guess I'm one of the unlucky ones as I can't play a single CD game on my K-model Jag
Tried different SD cards, never had any non-contiguous errors, just black screen. GD on latest firmware. The furthest I get is a second or two of intro video on a couple games and then black screen again.
I'm enjoying all the regular Jaguar games though, as well as the awesome ST ports and homebrew.