I haven't, but a 58L pack fully loaded isn't going to be allowed as a carry on, unless the attendants are blind. I doubt you could even get away with it mostly empty, the dimensions are just too big.

No, I think you'll get busted... You should just check it, but get the Osprey Airporter to put it in before you do - it will protect your investment!

I have taken the Exos 58 as a plane carry-on on several occasions. The key is to remove the floating lid/brane. With this part removed (I take it along as well as my "personal item" stowed under the seat in front of me), and the lower compression straps cinched slightly (reducing the depth by ~1in), the pack fits the 9x14x22 size standard specified by most airlines. I even had someone stop me and make me put the pack in one of those metal boxes that carry-ons have to fit in; it works.