Mr Straxy is doing ok so far, I think. Since starting him on 1/4 pill Cerenia daily (which is expensive at $12/pill), he has got his appetite back and is generally perkier.
He's also on mirtazapine, which makes a difference, but isn't enough without the cerenia. His (pricy but necessary) fentanyl patch is also helping greatly with pain management.
My vet says to treat the cat, not the numbers (ie blood test result figures). Although he is classified as stage 4 CKD, I think ol' Straxy is doing pretty ok on his current regime.