Natural balance is a very good food
Rotating should not be a problem unless your cat has a sensative stomache. A lot of people I know rotate their dog/cat food all the time to give variety (even different brands), I have never had a problem.
I really don't know about cats but my puppies get it once a day, it's really good for the digestive system. I don't give them flavored becuse it usually has sugar in it. They also love cottage cheese.