I've done my flying in Wanaka, too. Great mountain flying! As fas I know Ardmore for example has a lot traffic and you'll learn to fly in busy airspace. You'll get experience in flying controlled airspace in south island, too. But You won't get that much mountain flying experience in Ardmore... Those who have flown there can be more specific. I would recommend you to think what sort of flying are you trying to get after you have your CPL. In my opinion flying in mountains will prepare you in flying your helicopter and learn its limits. Flying in busy airspace helps you to speak with the tower. The tower will tell you where to fly... My two cents...