I have used and tested both classic and modern Sprint based phones. The service in Kentucky still is garbage. The polls also seem to agree. LTE/3G/whatever go into the country service dies completely. Hello to super hot battery and 8 hour or less battery life as it struggles to re-acquire a signal.
My needs aren't as picky as most, so voice + data doesn't mean anything to me since I'm always near a wifi when I use any phone as a phone. But, closest you get to that on Sprint is using a Wifi calling app or Google Voice. Sprint seems to be suffering from RIM-itis, the failure to move forward with the times.