Posted:a #13 chain weighs about 1 oz; a #15 chain weighs about 2. The #13 chains seem to fly a little faster (not necessarily a desirable trait), probably because of their smaller aerodynamic profile.
I'd argue that the #13 chains are a little less comfortable to grab for moves that require that, but it wraps around a tighter radius.
I've seen a couple cases where #15 NPS chains broke after about 16 months of hard use (in both cases, at the link entering a connector). Not enough data on the long-term reliability of SS chain.
Laugh while you can, monkey-boy