I like the Muenster and still use it on occasion for my dogs who don't have grain and chicken allergies. The DE isn't a problem - you'll find food grade DE in various livestock and dog foods. My chocolate lab still gets the Victor salmon and potato food.
I buy dog food sometimes at Tractor Supply, where one of their better brands has several varieties that contain no grain or chicken and it costs a few dollars less than Muenster. One of these days I'll be trying that brand on the lab to see if he tolerates it or starts scratching again. This isn't a very scientific process.