Only managed to read the first half of this thread so far - so apologies if I am repeating but...
Everyone against seniority seems to think that it keeps T&Cs lower than they should be. Is that the case?
Most airline beancounters would love to have every seat filled by a year 1 FO and a year 1 Capt (assuming the airline has yearly pay increases).
A regional airline I know is practically rubbing its hands with glee as the more senior guys (particularly skippers) are getting pi$$ed off with their lot and jumping ship. They can then hire DECs (or promote the more senior FOs who haven't done the same thing) at Pay Point 1 prices!
The chances of an incident are still low (as everyone is qualified/capable for the job they are doing - something which apparently doesn't happen in seniority driven jobs; failed your Captains check, no worries you are next on the list so here you go anyway
)
The promoted FOs even have worse T&Cs than the equivalently experienced (and in some cases significantly less experienced on type) new join Capts since they are historic from their original contract. In fact if HR would let them they would be better off resigning and reapplying (if it wasn't for their Type rating bond).
And personally (as a junior in my new airline) I am looking forward to choosing my roster in my 50s. In the non-seniority based one the guys were still doing the same old cr@p that I was up until the week they retired (the ones that stayed) That is something I don't want to do!