Cook sausage in a large skillet over medium-high heat, stirring often, 4 to 5 minutes or until lightly browned. Drain well. Stir together sausage, stuffing mix, and next 5 ingredients. Set aside.
Butterfly pork loin roast by making a lengthwise cut down center of 1 flat side, cutting to within 1/2 inch of the bottom. (Do not cut all the way through roast.) Open roast, forming a rectangle, and place between 2 sheets of heavy-duty plastic wrap. Flatten to 1/2-inch thickness using a meat mallet or rolling pin. Sprinkle evenly with salt and pepper. Spoon sausage mixture evenly over pork loin roast, leaving a 1/2-inch border. Roll up roast, and tie with string at 1 1/2-inch intervals. Place roast, seam side down, in a greased shallow roasting pan.
Bake at 375° for 55 to 60 minutes or until a meat thermometer inserted into thickest portion registers 145°. Remove roast from pan, reserving drippings in pan.
Stir together fig preserves, Madeira, and balsamic vinegar. Spoon half of preserves mixture evenly over roast.
Bake at 375° for 20 to 30 more minutes or until meat thermometer registers 160°. Let roast stand 15 minutes before slicing.
Melt butter in a medium saucepan; whisk in flour until smooth. Cook, whisking constantly, 3 minutes. Whisk in reserved pan drippings and remaining fig preserves mixture, and cook over medium-high heat 5 minutes. Serve sauce with roast; garnish, if desired.