Not really. As long as Volke is wearing enough to cover the shoulders, waist, and hips, he looks almost exactly the same when genderbent. Save for the Red eyes, slightly feminine tone of voice (that is otherwise completely the same), slightly softer face, and newfound space between the legs, he's exactly the same. But becuase a woman's hips are wider, her legs are a little further appart. Some people can tell male and female right off the bat because of that gap between the legs. So... No. No bonus, but no penalty, either.
Most people won't even notice the shift of the body, since he always make sure that she's properly covered so people can't tell. The only sign of the shift is the eye color change and a puff of smoke that comes from her body.. like when Ninjas transform in the Naruto series.
Although, if she were using her voice to be... less monotone... Speaking like.. Rather, speaking in a higher pitch while female or lower while male, it would probably give a +1, but only in the right circumstances. EDIT: Her voice isn't monotone, but... soft, and... tch... I don't really know how to explain. Rather... Volke tends to come off as emotionless due to lack of facial expressions and any real vocal inflection.