Apologies for the tardy response.

Lan's upgrade system works well for RTW/Circle Pacific tickets (Visit South America Passes?) where these tickets are booked in D class. The downside is these upgrades can only be confirmed at the gate. It's not so good for normal single/return tickets as the minimum upgradeable fares are far too high. It also worth well using Lan Kms to upgrade individual sectors as this is the only method of guaranteeing an upgrade before arriving at the airport.