to be honest having looked at the prices of the better wet foods and added the cheaper option of the classic i don't think it will cost much more than feeding lots of dry. mine can chomp through a hell of alot of dry food especially now it's colder. the wet seems to make mine fuller for longer. i guess as it don't have all the carbs in giving them sugar rushes and making their insulin levels rise and fall sharply making them crave more carbs and dry food. so i certainly think it's better for the cat and not all that expensive. they often have good offers on at zooplus and pets@home etc.
