I really like my exo 3500 in coyote. Have a few trips in the mountains so far. The packs rides really nice and very comfortable for me. Only loaded it up with about 40 pounds pounds so far. Also done only day trips but hopefully in the next couple weekends going to do a longer and overnight...
I just compared the exo 3500 to one of my kids carry on luggage bag and they are really close to the same size. The exo is maybe a inch longer and about same width. So imo it would probably depend on what you were going to cary on.