Everybody agreeing? But add me to the list. No furring strips and 2-1/2 or 3" drywall screws. If the installer that doesn't want to use the furring strips is adamant about the ring shank nails, or can give you a good reason why they are best, I would go that way. He does it for a living and might feel that he can control the nail dimples better. The ring shanks are not like using roofing nails that pop easily.