title: flux multiple store instances
body: <p>In a flux application where data is divided into buckets by owner id, should we use one store which internally separates the data into buckets, or one store instance per bucket? </p>
  
  <p>For instance, we have an application user who is a coach for multiple athletes. Each coached athlete has zero or more workouts, and the coach can view one or more athletes' workouts at the same time.</p>
  
  <p>We could have one workout store for all athletes; the store has to ensure that all data is separated into athlete buckets, and every store method requires an athleteId parameter.</p>
  
  <p>Or, we could have one store instance per athlete id. This simplifies the store logic and method signatures, but then we have to manage more store instances.</p>
  
  <p>Does anybody have any experience with this approach? Any pros or cons of doing it one way or the other? Or, which way is 'the flux way', and why?</p>