Think as if you are all bean counters and not pilots.
Dash 8-300 to old and not really an option.
Saab 2000 made for crossair and there requirements not really anybody elses. Very expensive to aqiure new a/c and not cheap to upkeep.
Dash 8-Q400 to large to fast to expensive.
ATR42 Cheaper, commonality of fleet with 72 = sim in NZ training costs drop, a/c wear and tear due training drops, Overall a cheaper option for the long run.
I will even go as far to say that if they do get 42's it wouldn't surprise me to see Cook an NSN merge and become one company.
But thats just my two cents worth.
splat.