Been learning to hone and maintain a straight razor for a few months now. This brought a hanging strop into my sharpening world. I was stropping a razor a few minutes ago and thought about trying to use it on a knife. I had my SB Stretch in my pocket so I tried it. The results were really really great. On my hanging strop I have .25 micron diamond spray on the back (rough) side and nothing on the smooth side. I used the back side for my Stretch and it went from very sharp to VERY sharp. It already sliced into and through phone book paper with ease. After a few strokes on the hanging strop it is now much easier. It slices through the paper with less resistance.
Using a light, very light stroke for the finishing strokes on stones or strops is the key for the super sharp edges. I think that since the hanging strop has some "give" to it compared to a strop mounted on glass, wood or some other hard material gave the contact between edge and strop a very light touch. I don't know for sure but I do know it improved the sharpness. How it effects edge retention I don't really know. I do know the hairs on my arm now POP off instead of just pile up on the blade when I shaved my arm.
Since I've been practicing with the hanging strop for my razors for a few days I have a better feel for it so maybe that helps. If you have a hanging strop and haven't tried it on knives give it a shot, just for fun. Remember to keep the angle low and use as light amount of pressure as you can. Keep the angle the same as is on the edge or a little lower. NOT a little higher on purpose. When you try to keep it a TINY bit lower you will still hit the apex often enough for it to work.