I have been feeding Burns Mini Bites for about 2 years and only wish I had found it sooner. Fortunately my dogs have never had AG problems but they absolutely love the food.
There is quite a large selection and, hopefully, you will also be able to get samples from your supplier. All Burns animal feed seems to be well balanced, wholesome and nutritious. Although I hadn't read "The Science Bit" in your link before I can confirm the volume of my pups' poos is greatly reduced and so I have no reason to doubt that, as they say, their products minimise the amount of waste matter in the body which can cause blocked anal glands.