According to a person who had requested Notin Ink Pre-order Support for changing his order to Wifi only model since this 3G variant mystery, the NI has replied that the 850 also supports 800/1900 freq. and the 900 supports 900/2100.
After hearing that, I asked the NI if I could change my order from PQ with wifi only to PQ 3G model.
But my request was simply not approved because PQ variants already sold out. :-P