I've also only had experience with a kitty with bladder stones - but after learning more about what cats should eat and how incredibly *bad* prescription diets are (and the Hills stuff was included in the cat food gluten recall... which is what I think *started* my kitty's problems...) I switched him to Ziwi Peak and have never looked back....

One thing I heard is that those companies Hills, Royal Canin, etc pour a lot of $$$$ into veterinary schools and gain loyalty that way.... I have a hard time trusting vets that push the stuff these days... I'd see if you can get a second opinion from a vet who doesn't have one of those brands prominently featured in their lobby....