In the xDB world (ie in 7.5/8) we created a typical MVC controller & view to allow us to get information to the browser via a json feed. Example data would be custom facets we could import from other external systems into xDB, exposed to the browser via querying the xDB api with an identifier and then retrieving the facet data. Finally we'd render for the browser via a WebApi endpoint/MVC view.
In the xConnect world, is the best way to get this data via the xConnect client directly, or to expose the data as we did before through controllers and views exposed from the Sitecore application (and hence xConnect).
Is there any significant performance difference between the 2 approaches?