Disclaimer: I have some kind of vicious web of connections between apps: mapmyfitness...runkeeper...MS Health...mapmyrun...you name it, it's connected to as many others as possible!
Anyway, I can say for sure that pretty much 100% of my runs have included step counts on mapmyrun. Not sure through which app they got there, whether directly from Health or indirectly via another app, but they're there. These all synced as runs -- I can't say what would happen if I'd logged them as exercise instead.
-Matt
PS Something is obviously fishy with the counts though...who can explain how 3 runs have identical step counts? My pace is not
that consistent.