I just returned the 6L. My canon is mirrorless with my 24-70 lens ; it is to tall for it. I ordered the 10L. I do have a peak backpack, but use it as a shoulder one.
I own the Canon M50 (Mark II) with the Sigma trio (16mm, 30mm & 56mm f/1.4) I want to get the gray 3L as we all know the M50 (MKII) is a fairly small camera and no where as large as his Sony. I believe I can fit my camera body, the 3 prime lenses along with 3 extra batteries, 2 extra extra SD cards, dust-blower & cleaning cloth in there.
I have the 3L & the 10L, they are pretty great. I bought the 3L for the same reason as you. Travel one camera thingy. Now, I will get the hand strap too. Just to mention, Peak Design warranty is amazing, because my old 10L Sling zipper broke, and got a new version as a replacement from PD. 👍👍👍
Thanks for the video! I have the 3L and felt like the 6L could be useful for an upcoming trip but wasn't sure if it was worth it. The 3L is probably fine but the 6L could be useful to store incidental purchases and a bottle of water or stuff like that. Decisions decisions!