And this is coming from someone who used to be a supporter of declawing. I was told all the usual, if it is done correctly, with proper pain control, it is fine and there are no lasting effects.
I even had my cat declawed when she was a kitten (radiographs have shown it was done well, had them utilize laser on her and kept her on a regimented pain control/confined schedule post-op to be sure she healed well). Now, 12 years later, I regret it. She has fairly bad arthritis now in her front paws, shoulders, and hips. Declawing alters the way they have to walk and redistributes weight/gait in a way that was not intended.
She can't posture in the litter box well sometimes and so ends up with urine/litter all over her back end that needs to be cleaned on a regular basis. She visbily limps around on occasion. Yes, I have her on pain control, but we all know there are limited pain control options in cats. The amount of times she has a urine soaked back end would have likely had her either surrendered or euthanized if she were owned by someone else.
It has been proven over and over that declawing increases, not decreases, behavioral issues and thus behavioral surrenders. Increase chance of them not using the litter box (because it hurts), becoming aggressive and using teeth since they are without claws.
There is just zero comparison in causing life-long pain to a cat by declawing them with a spay/neuter procedure. No comparison. Rather sad to see someone even try to compare the two.