1. Ported my Sprint # to GV, only use that for calls and SMS.
2. Use Google Hangouts for SMS from my GV # as well as Google talk.
3. Enable background data, then restrict it on an app-by-app basis.
I don't get any messages, SMS or Hangouts, unless I have Hangouts open and I'm staring strongly at it. This tells me that (a) background data is not working for hangouts even though I haven't restricted it, and (b) Google Voice is apparently using mobile data for SMS no matter what? I would expect normal SMS to come through regardless of mobile data setting.
I've quadruple checked all my settings and I can't see where the problem is. /u/silicon_reverie , I'd love to know what you think.