As you already know I recently bought and reviewed NARS Outlaw blush. I received request for swatch comparison with NARS Sin, so I figured I should look trough my stash and try to find more similar colors.
Sin is definitely more purple than Outlaw, actually the most purple among these 4.
Outlaw is the rosiest and the only one with the golden sheen.
Plum foolery would be the closest one to Outlaw but not as rosy, more pigmented and softer in texture and no golden sheen.
Flirt&Tease is closer to Sin but not as purple. It is more mauvey and has some sheen to it.
Top to bottom: Sin, Outlaw, Plum foolery, Flirt and tease
L-R : Flirt and tease, Plum foolery, Outlaw, Sin