G'day
nzers, may I too express a welcome to QFF.
What class are you booked to travel in? If
WHY, the cabins are not that much different, main thing is IFE is on a 2½ hour loop rather than AVOD.
Other than that the OTP may be an issue; how long is your transit in LAX.
One other thing, it is unlikely Qantas will permit you to change the booking without charge.
Certainly, they will advise it is not their fault if you booked it after they announced the substitution.