Seed and finely chop Scotch Bonnet pepper. Trim chicken of fat. In a large bowl, combine the allspice, thyme, cayenne pepper, black pepper, sage, nutmeg, cinnamon, salt, garlic powder and sugar.
With a wire whisk, slowly add the olive oil, say sauce, vinegar, orange juice, and lime juice. Add the Scotch Bonnet pepper, onion, and mix well. Add the chicken breasts, cover and marinate for at least 1 hour, longer if possible.
Preheat an outdoor grill. Remove the breasts from the marinade and grill for 6 minutes on each side or until fully cooked. While grilling, baste with the marinade. Heat the leftover marinade and serve on the side for dipping.