Thanks everyone - interesting. We will apply for Canadian passports for all our kids as my husband's Canadian. (Which means you can travell just about anywhere). I'm South African and trust me that's perfectly good only for paying taxes in SA!
In SA I believe it is generally thought that having a foreign passport is a mayor advantage. Although my family is genuinely not 'fleeing' SA, a lot of South Africans seek/ would want the freedom to seek refuge in a 1st world country.