Took the station bike with its studded tyres to Reigate Hill today to see how they coped with mud. These are the studded version of the road-going Marathon tyre so the tread is fairly road-friendly.
They were excellent. On the steepish bit just after the little footbridge I stood up and accelerated hard, got no slippage at all. They gripped very well even when the tyres looked caked in claggy mud. Good on wet roots too and the slimy chalkier mud you get along the exposed ridge. Quite amazing considering the studs only protrude about 1-2mm or so.