Damn stuff wouldn't mix with booze. The booze kept floating to the top...which in a way was good, because it meant whatever the crap was became almost tolerable.
I'd only do it with the Cane Sugar version, which I drink room temperature most the time. I wouldn't trust any artificial sweetener to not do something funky when heated.
In fact, maybe that's why they no longer advertise drinking it hot - HFCS or artificial sweeteners made it inadvisable.