Does anyone feed their dogs any of the foods from this range?

I was given a 2.5kg bag for a BOB win at a local open show recently with literature about the feeds. A free 'generous' sample was offered so I filled in my 4 dogs details (Ages etc.), posted the form. A week later the 'generous' sample turned up! 30kg of food!!!! It is 3 different types from the range for my dogs to try. Just wanted to know if anyone permanently fed their dogs this food (Supposed to be a 'working dog' food) and what do you think of it?

A couple of the varieties are wheat gluten free, and come in around £12 a bag for 15kg, I think.