The rp-200 is an all-around multi-effect unit and costs $150, The Whammy pedal only does the pitch shifting tricks and costs $200 .... There's a reason whammy pedals still sell , yeah?

Go try the rp200 , if the built-in whammy effect satisfied you , buy it ... But since you asked about fitting it into your Boss effect chain , I guess you're a single pedals kinda guitarist , so the whammy pedal seems more right for you.