I know the chains are the same size when new.
Maybe I wasn't maintaining my chain properly but my stock non-oring chain needed an adjustment every two or three rides. That thing stretched like a rubber band. This continued for a few months until I replaced my chain with an o-ring chain.
I ran most of last season on that o-ring chain and only made two adjustments which is MUCH less stretching than the stocker.
When I ran 13/49 I was using a 110 link o-ring and was on #8 of the snail adjuster, any more stretching and I would have had to remove a link which is why I made the comment in my first post.