I think my main worry for using treats in this particular fashion (being actually inside the dummy) is that some dogs may start to think that getting the dummy is the reward, which is only fulfilling the drive to chase, when a dog should be rewarded for actually retrieving the dummy. Some dogs may understand that in order to get the treat out of the dummy they would have to bring it back to you, but I would think that most dogs wouldn't understand the concept right away and might take up the habit of running off, which just creates a new problem.
I would think the point of these treat dispensing dummies is to make the dummy interesting to the dog, which is what rabbit skin or bird wings attached to dummies also do, but if the dog naturally picks up and retrieves fur (which the dog in question does), then use that to your advantage and find an appropriate dummy that fulfills that drive.
I'm not averse to using clicker training or rewarding a dog with food if the dog isn't a natural retriever. I've never used food in training for retrieves, because both of my spaniels are natural retrievers with great drive. I suppose if a dog is lacking natural drive, one has to find what works for that particular dog. If I had to train a dog that wasn't keen on retrieving I would back chain using a clicker and food, though personally, I'd rather not spend all that time training a dog to do something that it doesn't naturally enjoy doing. Perhaps the reason why most gun dog trainers don't use food in their training is because the dogs they train have so much drive that the retrieve is reward enough in itself? At least for me, this was the case for my own spaniels. I also use flirt poles to build prey drive and play tug with both spaniels, but that's beside the point.
