Well I checked the material data sheet on it, and they REALLY don't want you to know what it is. It's listed as "natural and artificial" sweetener. So, it could have LOTS of stuff in it, including ethyl maltol (I think that's considered "natural" but also, potentially, stevia. It may have some sucralose in it, but it definitely has at least one other thing in the mix.
Have you tried contact them and asking them directly? I'd be a bit frustrated to get a "sweetener" where I didn't know what was in it. Capella makes a "super sweet" that is pure sucralose (and rather strong). I like knowing it is JUST sucralose.
Best of luck,
Anna