One of mine has been on RC Maxi Sensible to gain weight and it has worked a treat. Best her coat has ever been so might try her on German Shepherd next.
The rep told me that I can offer customers a money back guarantee as long as 75% of the food is returned so ask if you can return it if you dog doesn't like it as I can't imagine that they don't do this for all the businesses that retail it. Win win situation I think