Yes, I did one last summer. Really, really fun!
We got to do all the SuperDogs tricks and crazy tunnels and relays. I had a blast.
However, I did find the day just too long and intense for Nutmeg and she just gave up by the end. They also handle eachother's dogs, so Nutmeg had to be held by strangers, which she *really* didn't like. They weren't rough or anything, but in their shows they do hang on to the dogs while the handler gets in position, so Nutmeg had to endure quite a lot of other people holding her, moving her around, etc. She wasn't wild about that but overall she had a good experience