Which Lens !!!
I have the 10-22 , 17-55 and 70-200 mk II . I looked at both the 24-70 [ also the new II ] and the 24-105 . I wanted something to cover the 55 to 70 gap . Leaving the 17-55 , I lost to much - either F stop or IS .
I don't think you will gain anything except a lighter wallet and lose WA and longer mm . Maybe the 70-200 mk II for candid portraits , but the 15-85 is the bestgeneral purpose / walk around lens right now .