There should be an easy fix to this. If the workout app can record and store gps data and if other apps can read the workout/heart rate data from the health app, they can simply allow syncing after a run. But Apple need to make these changes, so maybe not that simple.I use iSmoothRun also, and no, it isn't native yet. But it seems even when the native app is available, it will still just be a display for the phone app with HR from the AW layered in. According to the developer, the app only runs when you raise your wrist, so it isn't possible for it to be a truly native app that does all of the timing, pace calculations, etc. on the watch.
It's a shame Apple has handicapped the watch in this way.