I have been using the Vent from Neo-Instruments for the last few months on my other keyboards and have been thrilled by the Leslie sim. I now use it with my Audya with even better results. I have found the Audya presets pretty good, as a whole, but the Leslie sim on the Audya drawbars is horrible. By attaching the Vent to Aux out 3&4 and using no internal rotor, the sound is as close to a Leslie 122 as you will ever get without the real thing.
I started playing with a B-3 and a 122 50 years ago and I know what it sounds like.
pa4X 76 ,SX900, Audya 76,Yamaha S970 , vArranger, Hammond SK1, Ketron SD40, Centerpoint Space Station, Bose compact