Question about author loyalty, series loyalty and genre choice

Greetings all, I just want to warn you in advance that I've been rolling this question around in my head for a couple days and it still hasn't entirely fully-formed, so if this sounds a little vague, please feel free to moan at me.

Okay, I've read in a few places (no sources, but I do believe I've seen the statement made here) that a self-published e-authors' best bet for building a solid fan base is through the writing of a series of books/related shorts. Has anyone here seen evidence to the contrary, ie success stories that have not come about, in part, as a result of writers producing a series of books, but rather as a result of readers simply enjoying an individual style of writing and personal choice in subject matter?

As an extension to that question, how many people have experienced some degree of success while publishing in multiple genres?
I ask this because, while most of my work tends to be of a relatively dark nature, the genres that I actually write in can range from horror, to literary and sometimes tragic romance.
Would my best bet be to publish only the works from one genre that I produce, or maybe to publish different genres under different names?

Michael Davis said:

All my releases have cut across different genres: Romantic suspense, political thrillers, and SciFi. When the muse whispers a story in my ear, she chooses the genre, not I. I'm very fortunate my publisher cares only about the quality of the story, not its genre. Had them asked for section rewrites but after 14 stories, never refused one due to its category.

Click to expand...

This is pretty much where I'm coming from. I tend toward certain genres, but I'm somewhat all over the place, and I'm not all that comfortable with the idea of leashing the muse and trying to force the words to flow in a particular direction.

@ Nick: I've been lurking here for a while, so I've seen/read a bit about your success, which has been damned inspiring. My question for you is, do you think that maybe you've put more 'heart' into your Big Lake books than the others?
In other words, do you think they sell better because they're a series, or because there's an indefinable something 'more' to them?

Did that make sense?

Also true...
I guess I probably shouldn't be worrying about a formula, one way or the other, and should just get on and write what I write.

Alas, I can't help but occasionally cater to the mind gremlins.

Thanks all, for the responses thus far.