Well, it depends. If you NEED an ABC to get into advanced obedience, rally, agility, etc, classes with that trainer, than it will actually get you farther than a CGC.
But you can take your CGC anywhere, and I wish more classes would require a CGC for advanced classes. I mean if you are going for advanced rally, and you have dogs charging you, or they are having troubles getting the dog to sit or down.
Heidi Ho, Odie
Joy-Joy, Bear Cub, Hepsi-Pepsi
Cujo2, Karma Chameleon
Ramona the Pest, Kojak -- who loves you baby?
Tiny Tinnie, Susie's Uzzi, Kaiah -- The Baby Monster.