Although the K5 has all the harmonics of the B3 plus additional harmonics, I have created my own patches for the K5 based on the 9 harmonics of the B3. There is some detuning of individual harmonics in the B3 however.
Since the harmonics of the K5 are so clear, the interaction with the Leslie is truly marvelous, creating additional overtones that are truly magical.
Hammond bought out Leslie and they now have a new half moon clip-on product for a keyboard that will allow you to brake, slow or fast like a regular Leslie. The half moon switch I believe was made for the XK series of Hammond organ, but the Leslie pedal also has that TRS connection for the half moon controller as well. Very nice.