Who knew? Certainly not me! But I am nothing if not suggestible so...
I used the recipe in the NYTimes: 2T instant coffee, 2T hot water, 1.5 tsp sugar. I used piloncillo. At this ratio, I didn't find it atrociously sweet. Some of the recipes called for 2T sugar. That would probably hurt my teeth.
Kind of a fun idea to play with. I'd like to try topping a mug of barely sweet hot chocolate with a dollop of this stuff for a mocha version.
Edited to add that I used the whisk attachment to my stick blender instead of doing it by hand.