It depends on which Avons you are talking about. I've mounted an AM42 Venom on the rear of my bike, and it currently looks basically new with about 8000 miles on it. I would expect at least 15K out of this tire, and others have noted similarly high mileage.
Once I mounted my taller windscreen back on, I find that the Venom rear grips very decently. Apparently I use the taller windscreen to judge my lean angle, and am more confident cornering more aggressively with my current setup, but that's another topic...
As soon as my Pilot GT front wears out (around 20K), I may try the Venom front. Most here run with the Azaro on the front with the Venom on the rear, so I don't know if the AM41 Venom is a good tire or just adequate, hence the preference for the Azaro.