The valve is the same part number I believe. True the 2 piston caliper would take more fluid but once you ahve the system full the pressure should be the same.

I like the idea of buying a loaded caliper for GSX and then just getting rotors so it all bolts on. Can this be done as well for the rears? I am just wondering if the parking brake on DSMs are different--are some actuated calipers and others with the mini-drum set up inside the rotor?