They are not the ideal pedals for muddy conditions for sure, but they are not too bad.
Having raced in the 'soup' at the USGP in Madison & Fort Collins, I now have mixed feelings about the M980's utility in the mud. For the masters race on day two (Sunday) in Madison a few weeks back, we had moderate rain that ended just before the start offering soupy, sloshy mud that really did not seem to inhibit clipping back in after running (okay, fast walking
) through the mud. For the Fort Collins round, although the earlier races had light mist which kept the track relatively dry early on day one, the rain let loose as the officials started the callups. The rain quickly turned much of the course into a thick gooey muck and my Sidi Dragons and XTR M980 pedals got seriously clogged after the runup and with a bumpy downhill immediatley afterwards, it was a struggle to get clipped back into the pedals for many sections of the course during the race. Fortunately the slightly larger platform made it a little easier to pedal while struggling to clip back in.