I can't help you with that particular outfitter, but I am sure if he is associated with the NRA (or any hunting/gun related non-profit) I'd assume he is pretty reputable, or at least isn't a total scam.
What are you hunting while there? I assume stag and tahr?
Do yourself a favor...bring along enough money to hunt chamois too, if there's time. You're already paying $1200-$1500 or so just to fly to NZ...shoot as much as you can while there. I shot two chamois while there and don't regret the money spent one bit.
"Its not the dress that makes you look fat, its the fat that makes you look fat"---Al Bundy