If you allow a small amount of hypo to remain in a print, it decomposes slowly releasing sulfur compounds which coat the silver and protect it from oxidation much like sulfide toning.

Sistan, and other stabilizers like it contain similar sulfur releasing compounds in low concentration which work to stabilize the silver in a siimilar manner and prevent image degradation.

All of them are pretty much the same. And, you can use Sodium Thiocyanate instead of Potassium Thiocyanate by adjusting the quantity for the change in molecular weight of Sodium vs Potassium.

There is an article publised by Ctein on this subject. I recommend it to you all.

PE