FWIW, here's my Avon Cobra history on the XCT.
Installed at 9,400 miles, new one put on at 27,400. So, I got 18,000 miles on that front. Second front still fine (have about 6,000 miles on it, i.e., about 33,000 miles on the bike now, and just did a second track day on the current set of tires two weeks ago).
Installed at 9,400 miles, new one put on at 18,900 and another new one put on at 27,400. So, I'm getting about 9,000 miles per rear tire.
I tend to get tire changes at the start of a season, to get it over and done with. Thus, the longevity is greater than I get, because I don't want to be bothered trying to get the absolute longest I can get out of tires, if that would mean interfering with the middle of a riding season.
I run the tires at 40/42 F/R these days, although earlier on I was running them at 38/42.
2012 XCT (SOLD)
: HeliBars; Centramatics; PC-V; Lloydz air filter; 11" Madstad; Rivco LED mirrors; Doran TPMS; Stebel horn; Motolights; CustomLED trunk flasher; KewlHeel shifter; CycleOps trunk rack; BeadRider seat; Vibranator bar ends; Passenger grab handles; Powerlet outlets; Handlebar RAM mount; RicZ laydown plate; Brukus SaddlebagSecure; 14" flexible antenna; RAM cupholder on trunk; shock Schrader valve relocation.