I'm considering whether its worth switching tires come the November rains. ATM I'm running Maxxis Minion DHR II on the front, and DHF on the back. I'm not a tire afficiando, I can't say that I've ever noticed a difference between the varioux Maxxis tires I've run, other than the big difference between new and old (and bald). I also haven't convinced myself that one tire model is better for front vs rear. My tires wear at different rates so I usually only replace one at a time, and I put the new tire on the front.
That said, I don't like my front wheel slipping on roots during the winter, so maybe I should pay more attention to my tires. Bike shop sales people certainly think I should :-).
I'm curious, do many people find it worth runing different tires in winter vs summer?