Hoff, as you say it is seniority based. If two pilots joined on the same day with the same experience and one went to the ATR and one went to the 777 then they would be subject to the same opportunities, however given the ATR is the fleet that is recruiting heavily and not many SO's are being appointed, then it is not unreasonable to assume that the existing SO's will have more seniority, so will be able to bid for a window seat on the jet before the new ATR guys. This opens opportunities for the ATR guys to move off the turboprop fleet and into the jet fleet, albeit as a SO.
It may not play out that way in all cases, but it seems a reasonable guess as to how it will go.
Once in the jet fleets NZ is likely to come up as an opportunity before mainline Australia I would think.
Similarly the right hand seat of the wide body Jets would come up realistically only for those pilots who are reasonably senior FO's and in some cases some narrow body captains are bidding back into the right hand seat for lifestyle reasons, some of which is driven by the removal of the ejet fleet.