Prices ex-Namibia (WDH) are similar to those from South Africa.

Bora Bora is an issue with xONEs in that there's no Oneworld service from Tahiti to anywhere except Chile, so including Tahiti would require a surface segment between, say, Australia/NZ and PPT. You can use the Global Explorer product (mileage-limited) to get around the South Pacific, using Air Tahiti or Air Pacific (Fiji) flights as long as they're codeshared with Qantas flight numbers. But mileage limits might get in the way (34,000 max for business class, 39K max for economy.)