A couple of more questions:
1) Whats the power draw on the main power rail (QSD + Teensy boards combined)
2) Is it possible to add a waterfall display on the LCD? Are there any spare resources in the CPU?
3) Is it possible to use the ADCs on the Teensy CPU for sampling the I&Q (instead of the audio shield chip) and likewise use the DAC of the CPU to output the mono audio? Are there any spare resources / cycles on the CPU to do this?