ive been looking at the oceanmotions diverters as well... gotta convince myself to pony up the $$$ for the diverter and the pump to go with it.
as for the SCWD, i believe is is a mechanical diverter in the body that switches the flow between the two outlets. since it relies on the water flow to move the diverter mechanism, you will lose flow energy, and ultimately reduce your flowrate through the device.
~mike