sucralose is a chlorocarbon. most chlorocarbons are highly toxic. since sucralose is not easily fat soluble, it appears to be safe.
Which is all that matters.
there are also lots of studies that show that nutrasweet is safe. and none that conclusively show it is unsafe. i have not seen any studies that show that sucralose is clearly safer than aspartame. i would be interested in seeing one.
That's not the way this type of research is conducted -- they don't do safety
comparisons. Rather, they research what is
important: Whether each individual substance
is or is not safe. The research on aspartame is not as strongly positive as, say, the research on saccharine (which has long appeared to be the much safer of the two -- that's not
really the same thing as saying saccharine is safer than aspartame, but it's pretty close). Sucralose lagged behind, in my mind, because there was simply less research. Period. Now, however, the research is piling up, and each bit of research is more compelling in favor of a determination of safety than corresponding research for saccharine or aspartame. Sucralose is turning out to be the big winner.
as for being safer than sugar, maybe compared to extreme overdoses of sugar...
A level of overdose evidently regularly practiced by at least 6% of the population, and perhaps closer to 35% of the population. So I don't think characterizing it as an "extreme" overdose is appropriate. It seems to be a pretty regularly-practiced level of overdose.
So in the context of this discussion, given that they're going to order a dessert at a WDW restaurant, it is very likely that many children would be better off eating something sweetened with sucralose than with sugar or aspartame. It is a shame that the best choice, a sucralose-sweetened option, is not available.