I do use google voice on my phone, but really just for voicemail. I use my G.V. # as a local number, and the out-of-state cell number as the old number that all my friends / family remember from the past. Occasionally I do have delays receiving G.V. voicemail txts & messages, so I'm slightly wary of using it to replace all the Sprint services. Maybe it's just the latency of downloading the audio...
I suppose I would make all my friends / family edit their address book if it came down to an extra $10 or $20 per month!

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I do sympathize with your situation. I've had to consider (for complicated reasons) leaving the old plan that I'm currently on &
it looks like pretty much every phone company wants to charge well over $70/month for a smartphone with a dataplan.