This is the error message I get after activating this plugin:
Warning: Missing argument 2 for Nav_Menu_Roles::edit_nav_menu_walker() in /home/content/27/9233427/html/wp-content/plugins/nav-menu-roles/nav-menu-roles.php on line 91
I can see the logic in the menu area which is great, but it will not display the menu according to the user role.
I hope you are able to fix this issue. It will be a very powerful fix for many web-developers of wordpress.
It also conflicts with other plugins, i.e. SlideDeck2, which will also be an obstacle to overcome.