I just returned from a week long trip to Singapore with the PD 20L. It worked out really well for me. Gear was A7RIII, samyang 35 1.4, Sony 55 1.8, flashpoint mini, small battery pack, MacBook Pro touch 13 with charger, a samsung galaxy tablet, bose qc35 headphones, a hoodie and a bunch of accessories (flashlight, sunglasses with case, extra batts, hex wrench, bottle water, etc)
Loved the PD 20L. It was comfortable with the pack full going through the airport. When I walked during the day, I took out the non-photo gear to reduce weight. The capture clip made it super easy to access the camera as needed, and took weight off my neck.
The bag was great. I put the camera and lens on one side. Then less frequently accessed stuff on the other side. With the side I didn’t need, I used their theft deterrent loop to remind myself not to open the wrong side. Not once did I put my bag on the floor to get the camera, though my friend did every time with his manfrotto bag. Not only did his bag get dirty but it took longer to setup and put away.
Im also happy I got the 20L as I don’t like carrying a heavy pack. For a mirror less, the 20L should be fine.
If I don't stuff the bag as full, I can even carry the Zhiyun Crane Plus gimbal in it as well (along with the camera, lenses, flash)