Yes, I have. I have written about Neurofeedback a number of times here on the forum but perhaps not about LENS specifically.
I used to be a strong advocate for Neurofeedback in general, but my stance recently changed after a recent bad Neurofeedback session which highlighted to me why Neurofeedback needs to be approached with extreme caution in light of the fact that there is a lack of solid research done on the use of the treatment.
I had 1.5 years of Neurofeedback sessions, one every week to two weeks. Only two of those were LENS sessions. I had extreme reactions to LENS in the form of severe anxiety, panic attacks, flashbacks, etc. The LENS treatments can be done for varying amounts of time. Mine were only for a fraction of a second, practically the shortest you can get. My brain simply couldn't handle having a frequency sent through my head as it disrupted my functioning too much.
Ive done research on the adverse effects of Neurofeedback and there seem to be two camps of thought. Those who believe it is the next big thing and believe it when all of those EEG websites say there are NO side effects, and those of us who know this isn't true as we've experienced the bad side firsthand. But before buying into the hype, think about this. Are there ANY medical or therapeutic procedures out there that don't have any potential side effects? Nope. I'm not saying Neurofeedback won't help you, or that it hasn't helped other people, rather I'm saying to become educated about it and know what you're getting into.
As for me, I decided to stop Neurofeedback after a bad session which spun me into one of my worst episodes in almost 2 years. What went wrong? My therapist simply got distracted and didn't time my session correctly. I had no choice but to stop the Neurofeedback because something so seemingly benign causing so much harm?...well, I'm not willing to risk that happening again.
I wish you the best.