They SFC is still unbeatable for a diesel engine. And all the extra weight gets given back on longer range – you do calculations between an avgas engine and a diesel and even though the diesel is heavier, by 4-5th hour in the air, they saved all that extra weight in less fuel consumption. And from there on it’s just a win-win if you fly longer.
I would love to have a diesel-powered Aerostar if that ever becomes an option. Now that EPS engines have gone under, doesn’t seem too promising for diesel in the 350hp range.