Where will they fly them
In and out of SYD. The lack of gates in SYD at times has aircraft sitting on taxiways and 07/25 for 20- 30 mins, and it's going to get worse as more E-jets come on line. DJ need a larger aircraft and the -900ER suits them.
There will be no increase in B737 numbers, as the older -700's will be handed back which will be a great relief for crews and ops who have to deal with the payload problems on these 20k aircraft.
In a 1 class config the -900ER can carry 215 pax.