I've gotten many responses from those with private trees who have copied my information.
Earlier in my research, I wondered if those private trees contained wonderful secrets to help break my brick walls. Over time, I have usually found that I have far more information than they do.
These days, when someone new to the hunt asks for my help, I generally counsel them to start with a private tree. It is so easy to make mistakes when you are beginning. If your tree is public, then those mistakes are more easily proliferated. If you start out private, while you are learning, it is far easier to correct your mistakes and not affect anyone else.