In order to create a sense of flow and retained motifs yet at the same time stylistic diversity, a generative module could at all times retain several streams of 'subconscious ideas' that represent viable solutions to the composition. Each idea uses a different set of parameter values to create an independent behavior for each idea. In this sense, each idea possesses its own personality of sorts. The module's 'conscious' thought starts on any given idea stream. The conscious thought represents the output of the module.

At any given time, however, the module may switch to another idea stream. In this way, the style changes yet the other styles (and motifs) are preserved, because the module continues to process them 'unconsciously.' Effective stream transitions could be made when two streams 'intersect,' so to speak, at a given point. In other words, if the contents of stream A at a time t are similar to streamB at the same time, consciousness may effectively change from stream A to stream B smoothly. The idea stream will then continue off in another direction, until it intersects with another stream at another point.

Here's a diagram of these ideas:
As the diagram indicates, this module has three streams in its subconscious. The streams are being processed independently (thus they have individual characteristic behaviors) but in parallel. The box of consciousness starts on a given idea stream and uses the stream to determine the module's output. The box can switch, however, to a new stream based on switch conditions (such as instantaneous stream similarity).

I think that this idea represents a step forward in both coherence and creativity. I'll try to implement it soon so I can see how the theory plays out in practice.