Preheat oven to 350 degrees F. Remove neck and gizzards from chickens. Rinse chickens and pat dry. Tuck wings under and secure drumsticks.
In a large skillet cook bacon until browned and crisp. Remove; drain on paper towels, reserving drippings. Cover and chill. Combine 2 Tbsp. drippings (or melted butter) and paprika; brush over chickens. Sprinkle with kosher salt and pepper. Place chickens in 7- to 8-quart oval Dutch oven or roasting pan. Arrange lemons around chicken. Roast chicken, uncovered, 11/2 hours.
Using turkey baster, remove 2/3 cup pan juices; skim off fat and set aside for sauce. Tuck bunches of grapes around chickens in pan. Return to oven; roast 20 to 30 minutes or until chickens are done (at least 175 degrees F in the thighs).
Meanwhile, for sauce, in skillet cook and stir onion, shallot, and garlic in 2 Tbsp. drippings about 4 minutes or until softened. Add mushrooms; cook and stir about 5 minutes or until browned. Add tomato paste; cook and stir to combine. Add wine and 1/2 cup of reserved pan juices; cook and stir until thickened and bubbly. Stir in cream and herb sprigs. Boil gently, uncovered, about 5 minutes or until thickened. Stir in bacon. Serve chickens with grapes and lemons. Pass the sauce.