I have a pair and ran them last winter whenever I thought I could.
They have a sticky compound and on the road drag feel like your riding in treacle, when new you can hear them as they get pulled off the road. On soft ground they feel OK but not fast
In proper mud, what they were designed for, they are excellent, amazing. You can ride through mud when all around you are slipping.
Not sure when I’d ride them now as they are a pure mud tyre and unless our local trails get stupidly muddy it’s not worth the additional drag.
On a similar note all you really need is a pair of Ralphs – I’ve been riding these in all weathers and conditions and they are excellent at best and fine at worst – not the best grip in mud but enough if you keep the speed up. On everything else they are excellent and if you ride one tyre only you just get used to how it rides.