In a large resealable plastic bag, combine apple juice concentrate, maple syrup, cider vinegar, olive oil, Worcestershire sauce, salt, cinnamon and black pepper. Add pork roast and marinate at least 3 hours or overnight, turning occasionally.
Heat oven to 400°. Remove pork from plastic bag and reserve marinade. Roast at 400° for 15 minutes. Reduce oven temperature to 350° and roast an additional 40 to 45 minutes, until internal temperature reaches 140°. Place on a serving patter and tent with foil. Allow to rest for 10 minutes.
Meanwhile, heat broiler to high. In a bowl, combine butter, maple syrup and cinnamon. Place apple slices on a large broiler pan and brush with butter mixture. Broil about 4 minutes per side, turning once, until tender, brushing occasionally with butter mixture.
Place marinade in a small saucepan and bring to a simmer. Combine cornstarch with 1 tbsp water; stir into saucepan and simmer for 1 minute.
To serve, slice pork and serve with apples and sauce.