Well I'm a bisexual girl DL, and even though I prefer guys when it comes to relationships, and can appreciate a guy with a cute face, nice arms, nice hair, good sense of style etc, I definitely don't get turned on seeing a guy in a diaper though. To me it makes him seem less masculine, and therefor less attractive.
I do, DEFINITELY enjoy seeing girls in diapers though. Maybe it's because even though I'm more attracted to guys in general, I can apprentice a women's body more. Or maybe it's the whole seeing guys as protectors thing.
Bottem line, I'd rather be with be with a guy than a girl, but girls look way better in diapers.