Her statment to me:
What is better for the cat? To be put to sleep in a kill
shelter or be declawed and live a happy life as a house cat
I hear this argument a lot. It is hard to fight unless you think of thess scenarios:
a) What if someone else,who WON'T declaw, adopts that cat before it is put to death?
or
b) What if complications come up because of the declaw and it DOESN'T live a happy life?

Is 15 to 20 years of agonizing pain (assuming a faulty declaw) better than a quick and painless death? And since there is no guarrentee that there will not be dreadful consequences from the surgery, you take that risk each and every time.

If having your furniture scratched by a cat's claws is unacceptible, then I can assume that if litter box problems arrise (And I can't guarrentee they won't), peeing on said sofa will not be acceptible either.