Don't worry about the mouse feet wearing out. Your mouse will die before the feet wear out. Also both surfaces will polish each other. Hard/ soft doesn't matter, each is acting on the other. A softer one will polish faster, but they both will wear down. Which is not necessarily a bad thing, if you like a slippery mouse. As the feet wear smooth, and as the surface of the mouse pad wears smooth, the mouse will get more and more slippery. If you like a scratchy mouse feel, i.e., a high coefficient of friction, then you will want to flip the mouse pad surface periodically to extend the lifetime wear, or just get a new mouse pad when it gets smooth (if you don't like smooth). As for the amount of time it will take, probably 2-3 years of vigorous mousing. But like I said, your Roccat mouse may die before that. Because even after 2-3 years, the mouse feet will still be in great shape, with some polishing. Also, I'm not sure which one you think is softer, the mouse feet or the mouse pad. Both are very hard, and very durable.