It could be as much as 20kg-25kg per person to 40-50kg total extra (depending on how much shopping we do). It makes the fares align more closely the more luggage we add.

I show SilkAir allowing 7kg carryon and 30kg checked, not 20kg. I'm doing my comparisons at 45kg overage.

In the end, it looks like it will be cheaper to send home a bag, even if it is 45kg. I am hoping that our friend can take it If this is a case, it is DEFINITELY cheaper to take JetStar and hope for no IRROPS.

In response to the person complaining about United, for the record I've had pretty good success as United Silver (60% upgrades in the last 12 months, very good phone support and IRROPS help). I'll make Gold this year, so hopefully it will get better.

Thanks again for all your help!