I too have several Osprey bags and use them for international travel. Overpacking on depth is where things go wrong,. You can pack tall and wide and still be okay. On the newer planes (Airbus A350, etc.) you are expected to load your bag on its side (not on its back).

I have several high quality travel bags including the Gregory 45l that you have and the Osprey Porter 30 Osprey a few years ago change materials at bit on both Porters.. The older Porters look and feel so much better then the newer ones.. The older Porter 30 are absolutely perfect in both how it carries and functions.. Now with the Gregory 45l I like the look and how it carries much better then the porter 45l. When I tried them against each other. Both are very similar with each having a few differences in the inside.. I would pick the Gregory over the Porter 45l But in the 25-35l category... The older Porter 30 is fantastic... I have the Patagonia Black hole 45l and the Osprey transporter 60l And a North Face 45l The Black Hole Patagonia 45l is a better overall better Duffle then the others... The Osprey Duffle was only better if you would use it as a backpack.. But as a duffel Patagonia function is better.. But.. For me there's a new winner in the 35-60l travel duffel I bought the Thule crossover 2 44l duffel and it's by far a much better duffle... And I bought a Black Diamond Stonehauler 45l Pro Wow... Both the Thule Crossover 2 and Black diamond stonehauler Pro are perfect.. Both are different but there's no comparison with these 2 duffel's Compared to North Face, Patagonia, and Gregory and Osprey.. Just my thoughts as a 58 year old traveler.. Blessings Greg