I haven't, but good friends have and had an excellent experience. They both work full time and so don't feel able to commit to their own dog, but this way they have a dog for evenings and weekends. Also, vet and food costs are covered so they also get a dog for free. Obvious downside is that you have to say goodbye after a few months... but at least you know that the dog is going off to do a very important job.
You considering it? PM me if you have any questions and I will try to answer based on what I know of my friends' experience.
