Solution
Any cPCI device (module or controller) may be used in a PXI chassis and any PXI device (module or controller) may be used in a cPCI chassis. A PXI module used in a cPCI chassis will not be able to route triggers and clocks through the backplane. Conversely, a cPCI module used in a PXI chassis will not interfere with the ability of the other PXI modules to route trigger and clocks through the backplane, but will simply not be able to route those signals itself. In either case, if you wish to share clocks or triggers then the communication must occur through the front panel of the module.

Note: It is important to make sure that the voltage rating of the device (3.3V or 5V) is consistent with the chassis.