Hey bitflipper, this is a somewhat nerdy "feature" indeed. But definitely an important facet of the concept, because the issues of the standard approach can quickly stack up in chains. If every nonlinear device does this, it's easy to end up with serious damage due to the successive bandwidth restriction (chaining a few of these oversampling plugs makes it more obvious). This is probably not super relevant for many ppl's workflows, though. In particular for typical mix-bus work. But the advantage can become easily audible given a wideband high quality source such as a HQ pre-master.
@gswitz: The delta signal is absolutely continuous, there's no on/off (this would produce distortion). It's just that the delta signal often drops to zero, and in this case, cancels out any (negative) effect of the resampling filters. Put differently, the resampling filters can only damage the "distortion", not the original "meat".
@mike: :D
Many thanks to everybody for the compliments! :)