According to the tests, Napa continues to lead both Sonoma, as well as a Sempron based system, in low power, even with the USB device plugged in.
Yeah, I'm sure it's really "bad news" for Intel when a faulty device driver brings their power advantage down from >50% to "just" 30% over an AMD based system. They had better recall those chips that don't deliver as promised, so that AMD is spared the embarrassment of a faulty chip that vastly outperforms it at lower power.