I think they have achieved a 7% saving in fuel burn, but don't quote me on that ! So just let's say they reduce fuel burn by 4%, on a thirsty 747 Classic, this means huge savings ! The classics of some operators will be around for some time to come, e.g. Kalitta or MK
airlines, so I think the programme would have made sense. IMO the fuel price was't high enough at that time.
Exceptions confirm the rule.