The only difference between the C2 and the C3 is that the C3 has a factory percussion unit that will do a second or third harmonic on the upper manual B preset.

My C2 with the aftermarket Trek II percussion unit will do 2nd, 3rd, and 5th harmonics and are implemented with sliders instead of rocker switches.
With this you can put in a lot of 2nd plus a little 3rd and/or 5th harmonics if you want. additionally, the decay is a slider as well, instead of the factory rocker that just does slow/fast.