Thanks for the feedback, much appreciated as always
I've seen elsewhere that the tackiness of the silver compound simply allows any fine dust on a dirty, dry track to stick to it and this makes them lose all grip. So unless the polished floor is swept very clean they aren't much use.
The yellow doesn't do this, but is still soft enough to generate grip on low grip surfaces, so I guess this is what makes it a great all rounder
Does anyone know about the block type schumacher tyre? I would gues that the edge of the blocks gives it more grip, but less forgiving than the rounded mini or full spike? Not sure how much they flex to aid grip generation though on low grip track, or if the edge componsates for this.