I say grab the 5160 while you can.
I have a 120 in stainless. It certainly sharpens up nice and easy.
Matching Christmas sets for the boys and I.
In my personal use, 5160 is a very lovely steel. I think I may like it more than 1095 (or other 10xx steels).
I have used professionally heat treated customs, and even my own backyard charcoal heat treat and find jr to be an excellent steel on a user, with the added benefit of being very tough. In a small folder that may not mean much, but the 120 is a longer blade, and will be subject to more force than you would with a folder.
As far as stain/rust resistance, I have not had any issues with mine. I tend to allow patina, and even force a patina where I have concerns.
I find 5160 to be less rust aggressive than 1095, 1080 etc. It is certainly less rust aggressive than my experience with 52100 (though I also love that steel).