OK, just wanted to share the quick evaluation I did.. The Ajna loaded up just didn't feel great on my back at all, I could feel it (my back) starting to hurt almost immediately. The Ortleib on the other hand was adjustable to the point where I got it to feel much better, and the waist straps on the Ortleib were much much better for me.
As far as packing my gear, I started with the Medium Shallow ICU and added in a Small Pro ICU. Both of those fit in the Ajna and Atrack 45L no problems. The Anja didn't have much room left over, the Ortleib had some, but not a ton. You'll see I've packed my loaner Cambo WRS into a dedicated hard clamshell, this took up much of the room left over in the Anja. For the Atrack 45L there was enough room left some some tightly rolled clothes or other small items. I will say the exterior pockets on the Ajna seem pretty well thought, and you don't get that on the Atrack.
Ultimately I decided to drop the Sony A9 / 28-75 lens and compact down to two Small Pro ICU's. This allowed me to fit them "stacked" in the Atrack 45L which left a lot of room up top, even with the clamshell. At the point I decided to go to 2 Small Pro ICU's I stopped considering the Ajna. Photos below!
Medium Shallow ICU + Small Pro ICU
Two Small Pro ICU (removed Sony from the packing list)
Two Small Pro ICU "Stacked" in the Ortleib Atrack 45L with Cambo clamshell on top, and room to spare.
Just to give you an idea of the spare room up top.. I probably could've put two 500C/M side by side.
Bonus.. two Small Pro ICU fitting pretty much perfectly in a Nanuk 933 hard case (with lid organizer).
I need to figure out how to use the side pockets in the Atrack.. I will probably keep them only partially full and lay them on top of the small ICU's for easy access when traveling rather than trying to stuff them around the sides of the ICU's. That way I just unzip and the first thing I run into are those pockets. Also the compression setup on the Atrack is awesome.. took me a minute to figure it out but I really like how quickly you can expand and shrink this pack.
P.S. If anyone wants to know where I got my sweet blue Croc-style slippers, just ask..