I did in June while connecting from an international flight at DFW. I had to wait more than 5 minutes to get someone to do the pat down and when I complained that I was going to miss my flight (inbound was late and long line at immigration) the person that finally arrived purposefully took as long as possible to do the pat down. Opting out ended up taking longer than 10 minutes (which is a ridiculous amount of time when you think about it) and I ended up getting to my gate just as the flight was closed. I sent a letter to complain to the TSA. It appeared that the TSA agents did everything in their power to 'punish' me for opting out of the new scanner, which should not happen.

That was the only time I was faced with the new scanners, but I will still opt out in the future even though I had the above terrible experience.