ok, I am hardly a chemist of any sort, but I think the xylitol-neurotoxin association may be because it is in the class of "sugar alcohol" and alcohol is considered a neurotoxin.
other than the other post in dental referencing research from toxocologists, I also have never seen xylitol with a negative association. Yes, it is known to be harmful to cats and dogs, but chocolate is harmful to dogs and we humans(luckily) have no problems with it.
If you ingest too much the only side effect listed anywhere is diarrhea.
I truly believe that the addition of small amounts of xylitol and having my children rinse with a dilute xylitol+essential oil mouthwash has eliminated cavities in our house. We don't do fluoride.
My dd (now nearly 7 and cavity free for 4 years) had serious cavities at age 2. It was really awful, her front teeth were reduced to yellow nubs. Once we added the xylitol rinse/occasional xylitol gum, everything changed. My son has never had a cavity and my dd's permanent teeth are beautiful.
I would never use it as a "sugar substitute" but we don't use sugar either. And it's not organic or crunchy in any way, but I prefer it to the alternative.