I'm working on a similar project now. If using 100 percent nitrogen, it shouldn't have to be in the for a week, since you're really just using that gas to push it out. You're right that you don't want to use co2, since that gas itself has an acidic flavor, and nobody wants fizzy coffee. If you're really into getting that cascade effect, I don't have. Definite answer for ya, but I'm about to push cold brewed coffee through a Guinness style faucet with all nitro, so ill let you know how it turns out.