Wow! 29 lbs! Do you have one of those giant Maine Coons? The CongoCoon? Mine is only 17 lbs and he's a big boy. As for the wet vs dry food, most modern vets i know believe now in "wet being superior over dry" cat food due to cats' not drinking much, most of them are thought of being "subclinically dehydrated" and wet food provides little extra hydration. My take on it is: feed them what they want/like to eat bcs their life span is short and they might as well live it to the fullest enjoying all simple pleasures of living" I used to have what my vets called "morbidly obese" 2 cats. Both towards the end developped hyperactive thyroid and got very skinny, then would not eat... it was heart breaking to watch them waste away like that. I'd take a fat, happy/jovial cat at any time
Love your theory in just making them happy.