New Google Hangouts Dialer App Provides Free Incoming/Outgoing Calls with a Data Connection

With an update of the Google Hangouts app to v2.3 and the introduction of the Hangouts Dialer app, it is now possible to place and receive calls using just your Google Voice number and a data connection. I've been eagerly anticipating this capability for a long time, especially since GrooVe IP lost the ability a few months ago.  Did I mention it is free, at least in the US?  It seems like these updates made my wish come true, but there is one thing that I can't figure out.  But first, downloads.

Getting the Updates

Droid Life posted an APK of the v2.3 Hangout, in case the Play Store doesn't give you the update automatically:

    com.google.android.talk.2.3.apk

Naturally Android Police and APK Releases posted their own links.  Take your pick.

Screenshots

Hangouts Dialer

Incoming call ringing in Hangouts Dialer

Incoming call ringing stock Android dialer

The Caveat

I already had my Google Voice number configured to ring my cell, which means this new Dialer and the built-in Android dialer BOTH RING on an incoming call. Sure, the solution is to disable forwarding to my cell in Google Voice settings, but what happens when I have no WiFi and no/poor mobile data, but do have mobile voice coverage? There needs to be some coordination between Voice and Hangouts so that Voice can be set to not ring your cell when you have good data rates (when Hangouts can handle the call)! Am I missing something? Should I permanently disable Voice forwarding to my phone and risk missed calls when data connectivity is suboptimal?