Absolutely agree that I wouldn't use my best sipping whiskey OR whisky. Even hearing of folks using the finest in mixed drinks makes me shudder! One of my Christmas gifts was a bottle of fine LAPHROAIG. The only way to enjoy such a rare blessing is very lightly chilled (room temp around 65 degrees F.) and a tiny touch of good water.
The Irish Cream and coffee is good, but not the same as the step by step Irish Coffee.
Also, having watched them made by the dozens in the referenced restaurant, I recall the use of plain sugar, though darker sugars might please other tastes.
The wife loves one in the evening. If I want an evening of quiet, two shots of bourbon and she's off to sleep with a smile. Diabolical that!