I have to say I've had multiple cats declawed and they have never had problems after the surgery.
Working with other people's animals I have seen MANY declawed cats who are happy and well adjusted. Working in rescue I see MANY declawed cats who are no longer wanted because of a change in behavior (and usually NOT for the good).

I think what people need to ask themselves is....."Is it right to take the risk? One that is irreversible once the damage is done."