I'm in the same boat of not understanding the differences in: CO2, Nitrogen and Beer gas. Do you use 100% nitrogen or when you have a stout faucet, do you use Beer Gas which is a mix of 70/30 or so? I've searched a bit but couldn't really get a definitive answer. It looks like many use CO2 for your stout regardless including Beirmuncher with his stout although he does use a stout faucet. I think that was what it said in his recipe for his stout..