Helene Dryden wrote an answer about Gregory Deva 70 Backpack - Women's - 4150-4455cu in on April 8, 2014
I have a 16" torso (in between a size XS and S) I originally bought a size XS as advised by a sales rep at a local shop. After using the pack for a 10 day hitch deep in the Colorado backcountry I was left wishing I would have gone with the Small size instead - the shoulder straps were a bit too short and dug into my sides.
I eventually ended up returning it.
A year later I found myself buying the same pack in the same size but switching out the shoulder harness for the small size. The XS pack with the S shoulder harness turned out to be the best fit for me, oddly enough.
I have heard of other people having to do the same.
Personally, I think the Deva is the best expedition pack for women on the market so it was worth it to me to go through some trouble to get it fitting properly rather than downgrading to a different pack.