Does anyone have any experience with http://www.renavast.com/ ?

Seems like if kitties live long enough, they all have kidney problems. Cammie-Cat is over 20 and is in kidney failure. Thought I'd start the 2 younger ones on something to help their kidneys before they get older.
Waiting to hear back from my vet to see if he's ever heard of it or recommends it, but I thought I'd ask you guys too.