I had a user ask via private message for their e-mail address to be updated. So I went into their profile from the inbox and updated the e-mail address. I then went into the user's DNN user profile, and I saw that their original e-mail address was still there. So I updated it again. Are we to update user profiles twice for every update? It would make a lot more sense for these two things to be done at the same time (from an end user perspective).
I'm not a DNN user, but I believe there is a User Sync option that would have synced them for you after you updated YAF profile.
I also believe there are DNN profile and YAF profile, so on the surface, to me, it would make sense that both would need updating since YAF and DNN are separate pieces of software.
That being said, as I ramble more, I think having a Save (and then sync) option tied to the save event wouldn't be too troublesome to add (if not existing already) for YAF profile saving in the DNN module.