I wear a size 9.5 and have those in a med. I had a pair of larges and I think up to an 12 could have fit easily. Hope that helps some. So my answer is yes in my experience they do run true to size.
Question for you CWB guys. I bought my gf a 08 pair of the Ember bindings. She has size 7.5 feet and I bought her Medium bindings. Is that the right size?