The one thing that blows Leslie sims, for me, is the fact that a real Leslie chucks the sound around 360º. So you get the bounce off the walls and anything else standing close by, whereas the sim just outputs what would come from the front.
There is a complete three-dimensionality to a real Leslie that eludes all the sims I have ever heard. Once again, if you are only trying to fool the audience, they are fine, but if you want to fool YOURSELF...
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An arranger is just a tool. What matters is what you build with it..!