Distortion is a critical component to any Leslie simulation. Most classic Leslies had underpowered amplifiers, typically 40W, which were easily overdriven. The horns were also prone to distortion. Jon Lord famously powered his Leslie with a 100W Marshall head for the distortion. But even when not intentionally overdriven, they always had a relatively high level of distortion and noise. It's part of the characteristic sound of a Leslie.
When Xils Labs introduced their LX-122 Leslie sim earlier this year, the most frequent complaint heard about it was that it didn't get the distortion right. I have a Hammond XK-1, which includes a Leslie simulation. My biggest complaint about it is the built-in distortion effect only works well at extreme Jon Lord-type levels but doesn't sound realistic at gentler settings. I intend to demo this plugin with fingers crossed. $26 is a damn good price - if the thing works well.
[EDIT: First Impressions]
Well I've been mucking about with this thing for about an hour, and I gotta say I'm liking it a lot. There are a few features missing, or at least that I haven't found yet, such as an adjustment for braking and acceleration times or curves. There are also no mic position options, although the Width control kinda sorta does that.
One of my primary criteria is that the more subtle distortion settings be credible, and this plugin achieves that fairly well. It can get gritty without ever being fizzy, even at maximum Drive. I haven't figured out what the "Character" setting does yet, but it seems to be a filter on the distortion harmonics.
Another mystery setting is called "Modulator & automation protection", with 5 choices of ascending CPU consumption. I don't yet know what that one's about. There does not appear to be an actual manual (there's a folder called "Documentation" but it's empty), just the popup help text, and it makes no mention of this nor any other configuration settings.
The Absorption knob is a nice touch. At around 75% it helps the organ sit in the mix better.
AGC is an unexpected bonus. It means you can experiment with or automate the Drive parameter without actually raising the volume. I wish more plugin vendors offered such a feature.
As with all of Vojtech's newer plugins, this one's got a resizable UI. Yay. This vendor often gets dissed on KVR for his sometimes-confusing UI designs, but this particular plugin is about as clean and simple and obvious as I've seen. Except for some of the more obscure settings, nobody will struggle to understand this plugin from the get-go.
Also following other meldaproductions products' conventions, this plugin allows you to morph between up to 8 different configurations. I haven't experimented with this yet, but it looks like a cool feature. I imagine I'd use it to crank the drive and treble controls during an organ solo, or some other scenario where you want to automate multiple settings with a single envelope.
Only one real negative so far: with oversampling enabled it's pretty CPU-hungry.