No one has the answers to your questions right now, we are all awaiting the results of the FDA investigation.
I would take any dog food reviews with a grain of salt. There are no veterinarians or veterinary nutritionists affiliated with DFA.
Hope this helps, excerpt below from: http://skeptvet.com/Blog/2018/08/grain-free-diets-and-heart-disease-in-dogs/ click on link for full article and comments.
Bottom Line
Nutrition and metabolism are complicated, and the exact relationship between dietary composition, breed genetics, and other factors leading to DCM is not yet clear. It is too early to say with certainty whether the diets are the primary cause of DCM in these dogs or whether other breeds may also be at risk. However, it is clear that the idea behind the health claims for grain-free diets is speculative at best and very likely untrue. Extreme diet fads hardly ever turn out to be a good idea in people, and the same is probably true for pets.
If you are feeding a grain-free diet, there is no need to panic. If you own a golden retriever or other breed that has been shown to be develop DCM in the past, it makes sense to talk to your vet and potentially have taurine levels tested or other diagnostics done depending on the circumstances. The diet you are feeding may be perfectly fine, but it is also probable not any better than any other diet with more conventional ingredients, and there is now some small indication that it may place some dogs at greater risk for this preventable disease.
The links above to the FDA and UC Davis Vet School will provide more information.
