Maybe I will make TextSecure my default app. I'll give "the hype" a day or two to start sorting itself, while I have the "auto" stuff disabled in my current default app.

In my -and my lady friend's- experience, TextSecure is the the only app to correctly handle MMS group chat. We tried the stock Android app, the stock Samsung app, and Hangouts. They all failed to do the right thing in one way or the other.