I was inspired by Eugene Kim's YouTube video on converting the medium Cafe Bag to a camera bag. I bought the same insert, and it works really well in my Synapse 19 (pre-25 version). Here are a couple of photos of my S19 and its contents from a recent jaunt through a patch of Costa Rican dry forest:
The camera insert is inexpensive ($20 on Amazon, if I remember correctly), and it fits square into the S19's main compartment. On this particular day, I put it on top of a spare t-shirt and a pack towel because I wanted quicker access to the lenses.
Not shown is my camera, an Olympus OM-D M-5 and the kit lens, which I used to take the photo. All equipment is reasonably well protected in the insert and the S19. I can get at it reasonably quickly, but I haven't used other camera backpacks to compare.
I've also used this setup as an in-flight bag when I took along my camera. I was typically able to fit an iPad, a light fleet jacket, and some snacks on top of the insert. It was a snug fit, but there always seemed to be room for one more thing.
And below, the S19 up against one of the thornier inhabitants of the tropical dry forest.