I've not had good experiences with grooveIP or talkatone. And I don't like the fact that it stops my calls in gmail from coming through. I use IP Comms + Sipsorcery for the sip solution to google voice. Then I use csipsimple as the android dailer/app. With a sipsorcery google voice dial plan, you can make & receive calls just fine. The sipsorcery dial plan does the whole google call back thing for you.
sipsorcery costs $$$ though, right?
(fyi---i use this same method plus a tasker tweak on my galaxy nexus to give me better reception at home, where tmobile sucks)