Regular or Indoor formula

I'm looking for a new dry food for Hunter as he is getting bored with his current one. I like to buy small bags because he goes through them really slow. He gets as much dry as he wants but I have to put it down for him to eat because my cat with food allergies can't get into it. He only wants it about 3x a day and he only eats around 1/3 of a cup of it typically. He ate quite a bit more when he was younger. He gets 1 pouch of Wellness a day or an occasional can of chicken or turkey proplan as a treat. The Wellness pouch seems lower in calories compared to the canned wellness but he will only eat slices or chunks. So in total he is eating 1/3 cup of dry and 1 3 oz pouch. It doesn't seem like much food for a 14 pound 16 month old active Maine Coon especially since my skinny looking 12 1/2 pound female coon can easily pack away 12 ounces of wet or a whole cup of dry food (depending on what allergy food trial she is on). I was thinking of trying the Wellness dry this time but am not sure if I should try the Indoor or the regular formula in the blue bag. Since he isn't a big eater I'm not sure if the fat content is high enough in the indoor formula. I like that the indoor formula becasue it has high amounts of glucosamine because of his leg problems and higher fiber since he has long hair.

My Cats get Indoor but I am not sure if its ok for all of them. Sasha is a very thin Cat adn Oreo is kinds Fat.