In recent weeks, I've received a number of requests for the M data. I haven't yet written the paper releasing the data set, and probably won't until this summer. (I go up for tenure next year, and I'm fortunate enough to have several outstanding R&R's that need my attention more immediately than any manuscript that will need to go through at least two stages of review).
But I'm happy to share the data. For details on how the measure was constructed, see this post.