Second A_Lee's comments, since upgrades are typically only available via Y B & M fares, the coupons are not so useful. Of the four that I have received, I used only one when redeeming a *A award to reduce the mileage by 10k. I understand even that was further restricted so it is only awards on OZ now.

I have found that most of the sales offices both inside and outside Korea tend to just refer me to the call centre anyways. Previously certain transactions with miles required filling in forms and handing them in or sending to the local office, an unnecessary bureaucracy. If the online booking tool can replace all of this, I will be certainly happy.