I was just sitting there fondling both and pondering this very question but with a different scenario. I was asking myself if I was to survive in the wilderness and could only take one which would I take, and the 0551 would be my pick. While the 0560 is my new favorite knife, the 0551 feels like a tougher more solid knife. The frame and lockbar on the 551 seems more indestructible, and the lack of the bearing pivot seems like it would hold up better to dirt, mud, and lack of maintenance.