Aussie operators have generally been averse to buying new, so seem to accept that with a used turbo-prop they will have a few initial maintenance issues. Half a million or more bucks of savings on a used King Air or similar buys a lot of maintenance. Also, a canny buyer can often get power by the hour to insure against premature engine overhauls. Is this available with piston engines?
Unless they have re-invented the laws of physics I don't see how the proposed
twin will have acceptable engine-out performance. 10 punters, fixed gear and 350HP? Maybe OK in Europe but here in the summer?