Yes i agree with the sums, done exactly the same a few years ago, works out at 20% discount on the redemption ticket. However, flew syd-kl last september,paid for my ticket and enquired about a discount on the redemption
ticket but was told not avaliable. Will try again later when i book syd-lon flight,
i have enough mileage accrual to cover either way but it would be nice to know
in advance.