I'm not sure if the option is in the Fi app or the Hangouts app, but I allowed Hangouts to manage my SMS on the phone. It behaves as my Google Voice number did before: SMS (as hoped) and phone calls (not so useful in practice) pop up in Gmail as well as on the phone.
This is what I do, and it's reasonable. Annoyingly, I sometimes miss calls as my computer will start ringing 10+ seconds before my phone, so by the time I grab my phone, the incoming call has already been sent to voicemail.
