I try to add minimal chemicals to our tanks as well and use non-harsh products like Ich-Attack or Rid-Fungus (Made by the same company as Fish Protector) when possible.
I've not had to use Stress Coat because I can order Fish Protector online, so I'm not sure how it does.
I use both Prime and Fish Protector in all of our water and have seen that it's been good for fry, older fish, sick fish and even newly hatched cherry shrimp.

So it seems to be very safe even for delicate inverts and fish.
http://www.novalek.com/kordon/fish_protector/index.htm - this is a spec. page on it.