Just throwing in my two cents.

All of mine are declawed. Bach and Mozart were my husbands choice to do so. Mozart had a tougher time than bach did with the procedure.. but I can tell you that they are happy, playful, CRAZY kitties, that climb over everything and ANYTHING. It has not hurt them in the least..

Of course all of mine are INSIDE only and we don't have a dog.. so the defence issue was not an "issue" for us.

Eliza however..well when we got her ALL FOUR of her feet are declawed. We are unsure why this was done to her (my husbands parents got her that way)... She is inside with me, but with his parents (before they got rid of her) she was outside, which was BAD BAD BAD.. she got hurt a couple of times.

As for biting and not using the litterbox.. all of mine use the litterbox (they just prefer to let me cover up their jobs!), and biting I haven't seen much MORE of a tendency than they had before hand (in the two boys). Eliza doesn't bite often period unless she's playing rough with you.

So... I think it's just a matter of will that cat ever be outside, is there a need for it to have claws? blah blah blah. I don't know if I would have personally had Mozart and Bach declawed, because I don't mind kitty scratches. My husband was the one that said it was a must do.