It's normally always worth using up your segments.

Qantas fly SCL-SYD as QF, LAN codeshare on this flight as LA. Note that this segment is very hard to get on an xONEx as L/D/A iavailability is generally minimal.

Have a look at this route for the dates in question using www.seatcounter.com - look for availability in the booking class you are after. (D for Business, A for First and L for economy).