I find the absolute strap on my Aeronaut to be a bit uncomfortable after a while but in backpack mode it's great. I think the weight is too much for my shoulders no matter the strap. Plus with the extra weight you get more "swing" going which I don't like. Only problem is I normally have a backup as my second carry on bag and that has to be hand held, which works but isn't optimal.
I find the Aeronaut in backpack mode to be very comfortable.
I can again attest to the great flexibility of the Aeronaut suspension. Did a short biztrip to Manhattan. Quickly getting through the airport & navigating to the Taxi stand was done really well with my Absolute strap. But yesterday we decided to do a walk from our hotel on W 46th to Penn Station, then navigate to JFK via the Air Train. About 1.5 miles in 90F temps. I had one colleague rolling his bag along and another with a heavy shoulder duffel. Took me 30 seconds to get out my backpack straps and I was OFF! VERY comfortable (if a bit warm), then put them away in another 30 secs to have a streamlined profile through Security.