I actually have a Hammond B3 performance setup on my Roland Fantom-S. The midi tracks in the performance setup act as drawbars (and things like organ click and leakage). With each track, you have control over the volume of each drawbar, and all the sounds are layered together like a real organ. I can also set the effects to emulate different leslies and control how fast/slow the leslie fan rotates. It eats up polyphony, which is a bit of a problem with the Fantom-S because it only has 64-note polyphony. It may be a good solution for you if you have a set of organ setting that you like. You can set those up as different performance setups. Also, you have all the other sounds of the keyboard. If you like to mess with the drawbars realtime, then one of the board you mentioned, or maybe the new Yamaha Motif XS (with all the sliders) will be better. I hope that helps!
p_music