For those people who have both Nokia 6120c and Nokia E51 I ask to compare the power consumption in standby mode and during the conversation. By doing this you may prove that the SAR level of E51 can be High Only when WiFi is on.
There is a free software built specially for S60 3rd Edition, Feature Pack 1 which can test the power consumption, battery capacity and make any statistics you want. It's name is Nokia Energy Profiler. Just google it, download and check everything.
Try to use bluetooth or the same handsfree for both devices. Theoretically the difference in conversation and standby will show power consumption of radio. If this difference is the same for both devices than we can conclude that SAR level is almost the same for both devices. Hence, no worry.
Why nokia 6120, because it's the most close device with almost the same hardware (processor speed, etc) and software (S60, 3rd, FP1)