I flew and managed two Merlin III's for a corporation at one time. As the old saying goes never buy just one Merlin you'll need two. One to work on and one to fly. The performance, speed, payload and fuel burn are impressive on a Merlin they really are. And so is the maintenance required to keep one flying.
You'll be bit slower and burn more fuel in a King Air but you'll have way less headaches in one too.