This isn’t a simple name recognition issue. Yes, use a pen name if readers will be negatively impacted by knowledge of your books in other categories or genres (as with kidlit authors pubbing romance). The risk of losing out on positive name recognition in one category if the other does well isn’t big since such audiences won’t likely cross over in big numbers anyway. But think beyond that: You’ll be managing 2 professional personas. Will you need 2 websites? 2 blogs? 2 Twitter, Facebook, Google+ accounts? How will you handle 2 personas at your events? Your promo is mostly on you—can you build reputations for 2 “people” and maintain/promote them forevermore. If risk management isn’t an issue, stick with one name and make your life a whole lot easier.