The decision to declaw is entirely up to the owner of the cat.
However, if you /do/ decide to get it done I'd be VERY choosy about which vet you let perform the operation. Sometimes a vet can take off too much of the knuckle, making it painful for the animal to walk. The cat will appear suddenly clumsy after the operation (as in trying to jump and not making it) because of the pain in his paws.
I'd rather see a cat be (properly) declawed than an unhappy living situation.
And you may want to look into "Soft Paws". They're like $20, stick-on claw-covers. They're even non-toxic in case your kitty swallows them.

Just a slightly cheaper, less invasive option. And if they don't work for you you can always have him declawed after that.
I do know that many vets around here will NOT do cats over one year of age. Some will go ahead, but that seems to be the general cut-off point.