Don the Beachcomber and Trader Vic were masters of the use of overproof rums like Demerara Overproof rums like Lemon Hart 151. Many of their classic tiki era cocktails were based on the these fine and flavorful rums to bring out the wonderful flavors that made the great cocktails of the era.
Here is one idea you might try in order to understand all of the flavor that is gained by the use of overproof rums in your everyday cocktails. Be warned, these are very good tasting, but one is generally enough. Overproof means that it does pack a real punch.