I am expanding the Torani syrup experiment to include a couple of regular sugar-free syrups: salted caramel and Irish cream. They should arrive mid-week.
This is also going to be a test for me. I've long suspected that I've been allergic to Splenda (sucralose), but there's no test for it. These syrups are sweetened with Splenda. My reactions to Splenda have never been immediate, so we'll find out if extended exposure will cause a rash as expected.