EWR is my home airport, though I usually fly out of A or C. I have never had to opt out as they don't have MMW or backscatter at every line and it is relatively easy to do a self-directed opt-out (get in an X-ray line). You do pretty much have to go through security at the terminal you are flying out of, and the lines are long (15-20 minutes, up to over 1 hour). Also the last time I flew out of EWR the id checker agents were asking names of some passengers, and the very rude man who checked my id made up a little song about my birthplace on-the-spot and watched for my reaction. So just keep calm, stand in the line and when you get to the front go for a line with WTMD. (If you fly out of A, which has this peculiar 1-behind-the-next tunnel for security, almost any line will only have WTMD because there isn't really room for anything else.)