It is great that you are committed to feeding your cats a proper diet. Nutrition is so important to overall health.
I will weigh in on the side of your current veterinarian. I too advise my clients to feed their cats mostly canned food. Cats do need high levels of protein and not very much carbohydrates. There has been a change in thinking among the veterinary profession in regards to the best diets for cats. I believe many people think feeding dry food will help keep the teeth clean. It is my understanding that unless you are feeding a specifically formulated dental diet (look for the VOHC seal), dry food does not have a significant effect on keeping the teeth clean. I have seen many patients that prove this.
Many cats on dry food become overweight or obese and develop related problems later in life. Of course, there are cats who free feed on dry food their whole life and are very healthy and have great teeth but this isn't the norm.
So my recommendation is usually to feed a large portion of the diet as canned food daily and feed some dental diet or good dental chews daily also. Some cats need to have calories strictly controlled as well. Ask your veterinarian if you need to restrict calories based on your cats' body score.
The other added benefit of canned food is the increased moisture content which can help prevent bladder and kidney problems. Go slowly with the conversion to more canned food so you don't upset their gastrointestinal systems.
I agree completely with the above comments and wanted to mention that in my experience as a traditionally trained, holistic veterinarian I have had success in my patients using organic diets, many of which are commercially available. I have also had wonderful results with home made diets.
Dr Carol Osborne, DVM