You can tweak the Pro-Tac with a hard push or a pull while it's in its bracket to get the exact angle you need. Once set, it stays there and is still readily removable with a straight up tug. I prefer the Pro-Tac because I can push with my legs, my back into the pillow hard, whereas the the other had too much give to give me proper relief from spine curvature. The between the seat and pillion item looks a little more factory and cleaner lines overall, just too flexible for me.
