I have verified that the LG Viper is capable of doing simultaneous voice and data without LTE and WiFi. I set Network Mode to CDMA/EvDo auto and made sure that Wifi was off. I called another phone and left the connection open. I was able to visit multiple websites.
From what I have read internally, the reason this works is because EVDO and 1xRTT operate completely independently. The chips are completely separate.
Pretty cool, anyway.