I really like RC. Taycie is on one the RX diets and is doing wonderful. I know they have other food available that are not breed specific have you looked into those? As far as breed specific, and this is just my personal opionion but I really think you would be ok to try the Yorkshire Terrier one if you want.
Here is a link to there website that has other foods listed
Royal Canin Products
Have you talked to your vet about just keeping in the Gastrointestinal? They may also have some other recommendations as well.