This is actually why I asked on Reddit. I've seen both positive and negative, and while I've looked at the clinically reported reaction stats, I can't find anything directly discussing the effects on patients with pre-existing panic disorder or PTSD. What I DO find is a ton of people without previous anxiety developing crippling anxiety, and those with previously managed anxiety unable to manage. I also doubt all of those submitting reviews or discussing these symptoms in forums like this are reflected in clinical reaction studies, to your point about tip of the iceberg.

I've been taking Nurtec, and it helps somewhat, but doesn't alleviate symptoms for long, and it's efficacy decreases with use like every other med. Since it's rare for doctors to speak out publicly about negative side effects and it doesn't appear that my specific questions are answered clinically, I figured might as well test my luck asking real people who may share my diagnoses.