Where can I find the schematic for the development in this kit: XK9X-DMS-0

A schematic for the board used in the XBee PRO XS is not offered.

It seems like a huge design flaw to not include a switch, or at least some solder pads to be able to select between USB and Serial…

I had terrible problems with this board, and not being able to use the external header for a direct serial interface (on the green boards). A friendly application engineer named Brenton supplied me with a schematic to help me modify the board to make it function. If I could post it here, I would do it in a heartbeat… It was the voltage translator chips on the FTDI circuit that were holding the signal levels constant.

ftp://ftp1.digi.com/support/documentation/XBee-PRO%20SX%20Development%20Board%20Schematic.pdf