Rascal Flatts are America's most popular band now. Imagine how big they'd be if they had male fans. Not that there's anything wrong with testicularly challenged soft-rock-with-occasional-mandolins; when they latch on to a smartly crafted, emotional pop hook, as they did for several singles off the last CD, they will bring out the woman in you. Only ''What Hurts the Most'' has so memorable a hook here; the other power ballads have new producer Dann Huff further ratcheting up the melodramatic hokum, to diminishing effect. Still, Me & My Gang will be girlgantuan.