Some features are similar to Archaeopteryx. Erratic controls drums probabilistically, like Archaeopteryx, but where Archaeopteryx uses the technique to generate new rhythms, Erratic uses it to add variation to existing ones.
Elysium uses probability in a similar way - in fact many of Erratic's humanizing touches have equivalents in Elysium. However, Elysium's weak point is drums, and Erratic's whole raison d'etre is drums, so the two might make an excellent match. Unfortunately, Erratic is PC-only.
The developer's site includes a number of other plugins, some of which use probability in various other ways, and others - like Sumo, the sound-fattener - which don't.
