Narrating Indecisions

I still struggle with whether to use the same narrator for an entire series or go with the narrator whose voice best matches the book. So far, I've gone with the voice that best matches the book, especially when considering gender. This means I normally choose a man to narrate when the male main character has a stronger role and a female when the heroine appears more often.

In The Farmers series, a male narrated the first and last books in the trilogy, and a female did the second book. Because of some unforeseen circumstances, each book in this series had a different narrator. With the In from the Storms trilogy, Douglas Birk narrated the first and last books, and Jennifer Groberg did the second book because the main character there was a female. 

However, I'm beginning to wonder if that's the best policy. Recent research shows that listeners prefer a female narrator for books in the romance genre and male narrators for most other genres. Now, Jennifer will also narrate Off the Streets, but I don't know whether or not to have her also do the second and last book in the series, Without a Dream, even though it has a stronger male lead. Does it even matter? I want to do what's best and what listeners will enjoy the most, but it's hard to know what that is.

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