On my Tyros 5, I mostly use Rotary Speaker 5, which is quite acceptable to me. The slow/fast speeds and acceleration curves are pretty accurate and authentic sounding to me with this particular DSP.
I have used both a model 147 (tube amp) and Pro 900 (solid state) Leslie speakers with my Tyros 3 and Tyros 4 with the organ voice channeled through the Sub outputs. Both speakers heavy as ****, glad to part ways with them. Nice parked in the rec room at home, but too cumbersome to handle and transport as a musician ages into retirement.
Yes, definitely gave a more authentic sound as apposed to the rotary DSPs, but it depends on the individual. I have a Hammond/Leslie organist background, so I know exactly how that combination should sound, but presently running left and right light-weight powered speaker to the rotary DSPs on my Tyros. You can edit/adjust the rotary DSP plus tweak settings in the Mixing Console to fine tune the characteristics you want out of the rotary speaker/organ voice effect to suit one's taste. Okay, it would be a compromised method to get the Leslie effect, but using the effect in an arranger/style mix while you are playing, most listeners wouldn't notice.
If you want real authentic solo organ and authentic Leslie effect, you may have to lean towards an actual rotating speaker horn or a real Leslie. Again, my real Leslie days are gone and personally I am more than satisfied with the Tyros/Genos organ voices and Leslie effects. Supposedly a new Leslie and distortion effect on the Genos that I need to check out. Also a new Real Reverb DSP that might work well with the organ Leslie voices and effects.
Check out (46:00 - 1:12:36) in this Peter Baartmans demo, solo organ and organ with a style right after. Authentic enough for me.
Yamaha Genos Premiere mit Peter Baartmans - 06.12.2017 - 18:00https://www.youtube.com/watch?v=FVq81hUkoEkMarcus