That's tricky to evaluate, because you get the exact same narratives from people who claim sensitivity to glutamates, where we can be somewhat certain that there isn't a health connection.
It's easy to evaluate if you have seizures. You don't need to wait for it to be definitively proven to make use of the anecdotal evidence. If you learned that aspartame could trigger a seizure, wouldn't you be cautious and want to see if a change to your diet would reduce your seizures?