Caravan will glide 20+ NM from 10000 ft "if you're on top of things" maybe even 30 the last time I looked at the graph.... Multi engine A/C is supposed to perform on one and even increase your range.
Who's got the harder decision.
For my two cents the decision made after take off in a large SE turbine with 12+ lives on board is a tough one. Engine failure after take off is a little bit easier in something with guaranteed performance like a Kingair.
the bet is to get both if its going around. Id rather be flying a Caravan than a 152 or Nevergo any day.