My VoIP journey has been a long one. It actually hasn't been very painful, just long. And my wife loves the results. Google Voice has done a wonderful job blocking telemarketers and sending the transcribed voicemails to our phones via e-mail is a hit.
However (and you knew there'd be an "However"), Google has made it more "interesting" than necessary.
In a brief recap, my goal was to move off of AT&T for $50 per month onto VoIP for way less. I chose to use Google Voice on an Obihai OBi100. All of that worked great until Google pulled the plug on XMPP that Obihai used. I inserted Vestalink (ne OBiVoice) and that worked pretty good. I had 2 family members whose incoming calls were always choppy. The workaround was to give them the direct Vestalink DID number.
Then in a sweeping transformation of Google Voice, it seems that Google and Obihai kissed and made up.
The move back couldn't have been easier or smoother. I left Vestalink in place for E911 but I'll probably look at it again when my annual contract comes up for renewal.