My experience is anecdotal ofc, but my experience with DAF is a bad one. I was blown away by how well it worked at first, then over time the effect started to disappear. Over a couple of months it completely stopped helping. I thought oh well, back to no aids then i guess, no worries. Thats where i was wrong,. You see; when using DAf, the brain becomes accustomed to having that aid there all the time, so when you go off it, you feel like your stutter is even more prevalent and harder to control. It made me super depressed and suicidal by how bad it got.