Corn Syrup Alternative and Ratio

I usually don't even use sweetener when I make ganache. If you leave out the small amount of corn syrup you will have a less-sweet result but it should still be good. You can sample a small amount to see if you like it (just let it cool on your tasting spoon). Or, you can try using either honey or maple syrup (I would reduce the amount of honey to 2 teaspoons); I think the flavor of the maple syrup will not carry through though.