Friends with benefits?

So this guy and I are good friends and are talking about becoming friends with benefits (fwb for those who don't know). What do you guys think about fwb in general, and from close friends to fwb? 
Also, there may be some feelings there...on both ends. I wouldn't mind dating him and he feels the same. Is this a good idea? I'm feeling pretty confident about it but I wanted secondary opinions. Thanks!