HEAT oven to 400ºF.
MIX buttermilk and 2 Tbsp. each hot sauce and vinegar in large bowl until blended. Add chicken; toss to coat. Refrigerate 10 min., stirring occasionally.
MEANWHILE, mix remaining hot sauce and vinegar until blended; set aside. Combine sour cream and blue cheese; refrigerate until ready to serve.
PLACE bread crumbs and garlic powder in shallow dish. Drain chicken; discard buttermilk mixture. Dip chicken, 1 piece at a time, in crumb mixture, turning to evenly coat both sides of each piece. Place in single layer on baking sheet sprayed with cooking spray; sprinkle with red pepper.
BAKE 20 min. or until done. Transfer to platter; drizzle with vinegar mixture. Serve with vegetables and blue cheese dip.