First, again Zappos made me smile by their unrivaled customer service on this order! Way to go folks! Second, I played about 5 hours today - all on hard courts - and I'm very happy to report that the soles on the Gel Resolution 4 seems to be wearing better (meaning less) than did the Gel Resolution 3. The green out-sole at the toes looks a little silly but it seems tougher than the black rubber that was there on the 3. Very happy! One other note, the
insole is also different - and, actually, not particularly to my liking. The 4 has a white material that almost feels like styrofoam or some cousin thereof. I think I preferred the
insole material of the 3. But time will tell, I
guess. Still, my feet are not sore after today's play - so no real complaint here either.