Hills CD Prescription Diet?

I am currently in the same position as you - my cat has been on CD for 4 years now and the crystals have never came back but I feel horrible feeding him such low quality food - just today I came across Wysong Uretic feline diet at healthy pet food store - it supposedly does the same thing as CD but has better nutritional value - I am just about to call my vet and ask about the switch (even though I'm sure they will promote CD since they make $$ off of it)