Drain peaches, reserving syrup; set peaches aside. In a small saucepan, combine the vinegar, cinnamon sticks, cloves and reserved syrup. Bring to a boil; cook until reduced to about 1/2 cup. Strain, discarding cinnamon and cloves.
Add boiling water to syrup mixture; stir in gelatin until dissolved. Stir in the cold water and sugar substitute. Refrigerate until slightly thickened, about 35 minutes.
Coarsely chop the peaches. Stir peaches and pecans into gelatin mixture. Transfer to a 6-cup ring mold coated with cooking spray (mold will be full). Refrigerate for 3-4 hours or until firm. Unmold onto a serving plate.
This recipe was tested with Splenda no-calorie sweetener.