I haven't seen a decent Leslie sim project anywhere. The GGG board is discontinued and the layout for one in an old Freestompbox thread looked more like brain mapping than a project that I could do. Is there anything upcoming? Thanks.
In general, leslie-type effects tend to be more complicated than boost or distortion-type effects. A new univibe project is listed on the projects page under the modulation section, but I don't think the release date is known...