Gossamer Gear Mariposa vs Tom Bihn Techonaut 30

I bought a used large Mariposa but find that when it's heavily loaded it hits my ass, no matter how I adjust it. I love those packs but haven't quite figured out the fit and I can't really return the used gear.

Wonderful quality but small size and uncomfortable straps! I just got the "regular" size thinking it would work for a school bag but it barely fits my binder, it just has an awkward tight fit. I'm thinking about giving this one to my kids and ordering the large size that's available. I was also disappointed that the straps are painfully uncomfortable, they are thin, very durable but very thin (width wise). These thin straps make it uncomfortable on my shoulders, so now I will have to buy the shoulder pads seperate

6 ounces—significantly less than the medium version of the Mariposa with a hipbelt. But with only three external pockets (none of which zip), the Arc Blast is limited in its organizational capacity, and we find that it doesn’t carry a load as well. If pack weight is your number one consideration, it’s hard to argue against the Arc Blast. But we give the overall edge to the Gossamer Gear Mariposa for its added carrying comfort, organization, and durability

And as a personal item on flights for the same reason. I have a Tom Bihn aeronaut 30 for my main carry on, but if I have a chance to train on a trip I need something that will fit under the seat that will fit my gear and travel items (neck pillow, water bottles, books, etc. ), and also not be a backpack. I wish that defy made something similar to the Evo in terms of size and shape