No, there is no perceptible difference. Call quality is determined by many factors, including the CODECs used, and the overall quality of your internet connection, and competition from bandwidth-hungry applications on the same network.
Google Voice calls on an OBi are actually using the old Google Chat/XMPP protocol, which uses the G.711u CODEC. All OBi devices that support Google Voice do so the same way.
A device upgrade would be useful if you:
- need more than two Service Provider (SP) configurations, and/or
- you want multiple OBi devices to ring at the same time on an inbound call from the same GV number, and/or
- you want a device that has a warranty and is receiving current firmware updates, and/or
- you want to do some advanced-level things with the device that aren't supported on the 1x0 series.