Hmmm 15-85mm? It costs around 800$(750euro) Wouldn't there be an L lens in that price range? *Not planning to buy one soon, just curious.*
I am with Neuro here. Compare to the 18-135, the 15-85 seems to deliver superior image quality (I haven't owned the 18-135). To me, on a x1.6 crop body, the 15-17 range is far more important than the 86-135 range.
I had the combo 1DIIN + 24-105L, then I got the 7D + 15-85. I sold the 1DIIN. Then I sold the 24-105 and kept the 15-85. The 15-85 is the better lens on a x1.6 crop body.