I'm a fairly prolific guy who writes across a broad swath of genre. Conventional traditional publishing wisdom tells us that we must invent new pen names when writing in a new genre, lest the poor and easily mislead reader find disappointment when discovering that our existential horror opus is somehow differently written than the wainscot fantasy that they're used to. Disenchanted, they will avoid taking chances on your work ever again.
The matter is different in e-publishing, where your backlog is your greatest marketing tool. Ebooks can easily and conveniently link readers to other similar works, and thus act as affiliates in the process. The bigger a writer's library, the more entry points to his body of work are available to potential fans.
Where is the balance point between the exposure that a wide library can offer, and the dangers of brand diffusion with too many genres stuffed under one pen-name? Is each genre and subgenre better off as a separate author entity, or can we take a broader approach? Can an author's pen names link to one another's work, or will that confuse and annoy the readership?