Really liked the overall size of the bag + its feature-set, but was concerned w/the measurable size in terms of what the airline(s) might/will/not accept in terms of linear dimensions, so opted for the slightly smaller Osprey Shuttle model, which is almost as large, but definitely complies w/most airline(s) linear dimension requirements.  I do miss some of the features on the Sojourn vs. the Shuttle, but oh well, overall I'm pleased I purchased the slightly smaller Shuttle model.