Plato's been going since was 6 months old. Almost 2 and a half now. Got his CGC at 9 mo. Could pass his CD more than likely if they didn't hold the test so sporadically. I've been to several Rally seminars and Rally is okay, but eh. I like the more formal nature of straight up obedience training/competition. Promotes a sense of calm in my dog.
A private trainer is a lot different from a group obedience class, and in my opinion inferior in a lot of ways. Private trainers want to teach your dog stuff. Yet, it isn't their dog. This is their way of being worth their money. Your dog needs to listen to YOU, and listen to you in public. Just because you can hold up a piece of cheese and your dog will "sit" in your kitchen, does not mean if you are out with your dog in a park you can rely on it obeying your commands.
The distractions and socialization of a group obedience class cannot be equalled...not to mentioned they are ALOT cheaper. And group obedience training is a bond with your dog, something that someone else does not need to do with you dog. There are only so many commands a dog needs to learn, and once you know the technique for teaching them, I don't see how a private trainer is helpful in any way whatsoever. I could describe how to teach every command right now in a 10min post.
...unless someone is seeing a private trainer for serious behavior issues, that is entirely diff.