I've been using RC for several years and Joey's doing fine on it. We switched to another brand and he started getting eye gook, so we switched back and everything's is fine now. Joey never has gas, or vomiting or diarrhea, and his coat his really shinny and his teeth and breath are good, so it really works for him, but it does contain corn, and some dogs are allergic to corn and have itching problems. Your puppy may have eye gunk because of teething too, it's not always related to the food. Here's a good article on eye tearing.
Tear Staining: The Causes & Cures