I have tried connecting to my X-Pro using an XBee plugged into the board. After changing the XBee baud rate to 115200 it works fine up to a point. The problem occurs when actually running GCode from G-code sender. After a few lines the Xpro resets. Occasional 'g-code not recognised' errors also occur. All the cables are screened and the errors also occur, but not so often, if the motors are disconnected. Clearly there is some corruption entering the serial data stream. Is it possible to reduce the baud rate that the Xpro and XBee communicate at? Or are there any other suggestions?
Did you ever resolve this? I was thinking of trying an XBee connection. Looking at the schematic, it only has RX/TX/Power/Gnd, so there is possibly no flow control, which would correspond to the problem described.