The dynamic arranger on Rolands varies the relative volume of the accompaniment parts based on how hard you play the keys in the chord section. So I guess Roland's implementation is pretty close to what the KN's was. A nice feature with a lot of room for creativity, but there's nothing random or loose about it.

Korg has a feature used when RECORDING guitar tracks for styles or pads, called "humanize guitar" that's similar to what Bill asked about. But I only think it affects the recording, I think playback would be the same every time.

Also the Tyros 5 and Genos have a "humanize" parameter (random timing) on their ensemble voices. Of course these are RH voices, not the style.