I have... but only the first time I tried and came close. Every other time was just blackness and nothingness. I think I've told this story here before, but I don't mind repeating.
I've never wanted to CTB myself; I've always wanted to go out with someone else's help. Back in the '90s, I went through a period where I offered to pay people to do the deed for me, and I had two girls I met on the street who took me up on the offer. Unexpectedly, they showed up at my house one night and said that was the night, so I let them. They chose to have me lay on the floor while the older of the two stood on my neck until it was done.
At first, probably for about ten seconds, I didn't feel like anything was happening. I could feel her weight pressing down on my neck, I could feel her tiny little movements as she tried to keep her balance, and I could feel the texture of her sock on my neck. I could see up her shirt, which distracted me, and I barely noticed that I was starting to get a little lightheaded. That whole experience took maybe ten seconds, give or take, then...
...then I was a bird. A white bird, though how I know what color I was is beyond me. I was free, and soaring. I was over a big city... a VERY big city, maybe New York, with lots of lights below. I can still remember, even 20+ years later, how I would catch the updrafts and soar over the light up buildings. There was traffic below, I could see it, and could even see people walking around, dressed very nicely and going into and out of the buildings. It felt so free to just be soaring along, riding the air currents, flapping my wings when I wanted, and not have a care in the world.
Then something happened. In my mind, I got shot, but it could have been anything. My left wing wasn't working right, something had happened, and I was falling. I could feel the acceleration, could see the lights getting closer, could see the tops of the buildings coming close then passing me by, and even the lights as I fell past them. I was going to land in the street, I could see traffic and even yellow taxis, I was headed for the street, and...
...and I felt myself take a big, deep breath. I was back in my home office, on the floor. The girls were off of me, and huddled in the corner. One was very pale, like she was going to be sick, and they were both trembling. Later, they told me they had stood on me for almost ten minutes, and they were sure it was done. They were trying to figure out their story when I took that big breath and came back.
That was the first time I really, truly came close to exiting. I don't think that's the closest I've ever come, because I've been really close a few other times, but it was the only NDE I've had. All of the other times it was just... nothing... like the world didn't exist and neither did I for those few seconds/minutes. But that one time is something I'll never forget.