They are very comfortable on your shoulders. I have traveled with them, walking through airports fully loaded and didn't have any shoulder pain. There is also a sternum strap to help with support, and you can buy the hip belt attachments for even more support. Definitely recommend this bag.
I was just considering to buy this bag as they've been re-targeting with a lot of ads.
I'm pretty sold now on reading your review! Was wondering how do you find them on your shoulders?