I would not get your hopes up on iSmoothrun solving our watch running app problems. I had a conversation with the developer a few weeks ago and this was the response to iSmoothrun running native on Watch OS2:
"I am still not sure what the best use of apple watch will be. It's tricky to work with it.
I am porting the app to watch 2 add HRM support and more interface stuff, but I ain't gonna port more core functionality to the watch for the moment."
Quite frankly, if Apple were to allow a smart bluetooth foot pod to sync to the watch - similar to what Garmin has with their running watches - then a runner would be able to go out running with only the watch and have decent distance and pace information and, when paired with a set of bluetooth headphones, music as well. All without needing to take an iPhone along for the run. This would also solve the problems of running on treadmills or running on indoor tracks. Adidas makes a smart bluetooth foot pod that already syncs to the iPhone running apps so this should be a no brainer. None of the running watches - Garmin, Polar, Tom Tom or the Apple Watch - do a good job by just using the accelerometer. Even iSmoothrun using the accelerometer on an iPhone is off by at least 10% in terms of distance.