Easiest way to compare corrosiveness, quick and dirty test, is to flash BP on one surface a couple times, then the 'other' stuff on another surface, then let them sit for a couple days.
When I used the Chlorate/sulfer/charcoal for caps, the barrel around the nipple rusted and looked to be finely pitted like a & 150 year old gun. That took only 2 or 3 days.