We started training a formal dumbbell retrieve last week and its been (so far and touch wood) surprisingly easy to train. I had attempted to teach Pepper a hold command with normal objects about 6months ago but she never really got it, so I imagined lots of dropping and chewing of the dumbbell. But we just started right from the beginning with tiny baby steps and she rapidly (within 5 minutes!) had a good sustained hold with no mouthing. Such a good girl. And man does she love the dumbbell, we worked lots on building drive for it and now she starts to screech and bounce and yowl when I get it out.
Because its been so wet we've done most of the training inside, I can tell you that a wooden dumbbell vs wooden floors isn't the best, wish we had carpet!
Last night I taught her the turn around and back up between my legs trick. She thought it was very exciting, although would get a little confused and start offering the occasional backwards circle (which shes never been taught) or would just spin and leap.