I ended up replacing my front Pirelli Diablo Rosso II at ~6000 miles. Its hard to tell from the picture, but on the front all the wear bars are gone, some of the grooves are gone and the groove depth is really shallow.
The Rear has the same miles on it, but it looks like it is going to last another 3000 miles. That is the reverse of what normally happens.
I ended up replacing just the front with a Bridgestone bt-45. I'm sure its fine, but it seems narrow, and the sides are so steep, I will never use the edge.