I like the idea of track power, but I suspect adding a choke may be necessary to solve the DCS compatibility issues. Note that many Legacy and even some TMCC locomotives require an RF choke to avoid interference with DCS locomotives. I suspect Barry's comment is based on experience with folks having issues with them on track power, so something would probably have to be done.
AFAIK, having a common that encompasses the switches should not affect the DCS signal.