Hmm tricky call. I think `.userId()` is ultimately the way to go in terms of giving you good data. The original reason we had added `.username()` was for mixpanel, but we should probably remove it.

The main problem is that there are too many edge cases where a user could include `properties.username` without much benefit. It means you also inherit the problem where if they change their email or username, all of your information on a user is lost. Not to mention doing `username` as part of event `properties` is just weird. Now that I'm thinking about it more, we should definitely remove it (@amir)

I think what's better is if we send you `userId()` as well as email, first name, and last name. Then your frontend could decide to display those differently if it has them for a user.