Depends on what your definition of a runner is. I'm a runner and cant imagine an activity tracker watch replacing my dedicated Running/Tri computers(ie watches). You can use Nike + but since it does not work with my HRM+ it's of no use. Same goes for S-Health. I also don't get the 'not wanting to run with phone.....' I run with my Note 4 either in pocket or in a arm band - no problem.
In winter it's no great deal as I usually wear track suit trousers (pants to you Americans lol) and can have my phone in my pocket but in summer I wear shorts and have no pockets and there's no way I'm wearing one of those arm band things...they're so uncomfortable and they don't look great. I'll compare the Gear S stats against my Garmin Watch for a few long runs and if they are compatible then what's the point in still using the Garmin when I can carry one less bulky device?
sent from my Galaxy s5