My honey ginger syrup was happily deployed and turned into awesome ginger ale.
The first batch turned out not very ginger-y and definitely not strong enough for me. So when I made the second batch, I increased the amount of ginger (which, this time, I didn't blanch in boiling water, either) and also put some extra lemon slices and cinnamon. I did go easy on other dry spices, as Chika suggested.
My second batch was a success! I made enough syrup to fill the Bonne Maman jam jar (370g one), and that disappeared rather quickly.
FYI: You need quite a bit of this syrup to make properly ginger-ale-tasting drink. The jam jar full of syrup made only about four glasses of ginger ale -- I need a bigger jar!
I haven't tried mixing this with sparkling wine yet, but I'm having dinner guests soon and that's what I plan to serve as apéritif .