Hi Steve,
if you refer to me, I use a PCap01 for my sensor not a NASA bridge. It's cheap, low power as per principle, has a DSP integrated that is sleeping while measuring so the complete calibration can be integrated writing some lines of assembler, needs only a few external components and has 3 additional resistive ports beside 8 capacitve ports. And since I fully understood how to configure it, how to programm it and how data has to be processed to get the best results, there is no need for me to use FDC1004. Nevertheless, we have evaluated FDC1004, but with worse results compared to PCap01. So PCap01 became the best sucessor for expensive and "dumb" AD7746 chasing atto farads, at least for me.
-branadic-