Well my take just depends on your definition of "friends with benefits." If it's just someone you go places with (movies, mall, or just hang out) then I don't see a problem with it. You're still basically just friends. If the "benefits" evolve into something more physical I disagree with it. It can turn into an ugly situation. He/she could end up falling for him/her when he/she just wants the "benefits" and not the relationship.