No, the Thunderbolt doesn't support SVDO. Voice uses the 1x radio path and data will use the EVDO/LTE network. Simultaneous voice/data will only operate in the LTE footprint. If you don't have LTE coverage, the same limitation will apply. SVDO allows the voice and EVDO data stream to access the radio network at the same time. The implementation on the Thunderbolt is more akin to having WiFi everywhere. Voice will access the same path and can set up a simulatnious session on LTE for data (due to the use of a dedicated modem chip for LTE, the MDM9600).
It would have been nice if they had used the chipset to enable SVDO on the device, but sadly they did not...