The basic concept is not to completely hide a view controller when a new view controller is being shown. FRLayeredNavigationController still shows some pixels of the view controllers the user passed through until reaching the currently active one.
This gives the user a good idea of where (s)he currently is in the navigation hierarchy. If the user should need more information of these partly covered view controllers, (s)he can always reveal the covered pixels by intuitive pan gestures. The user will think of a stack of paper and has similar interaction options.