I find this to be a bit trivial since most people homebrew at their homes and its very hard to regulate what goes on behind doors. I mean, I've heard stories of people brewing on the porch and neighbors calling police because they think its a meth lab, but thats a tad extreme, and at that point I doubt a responding officer will know enough about federal regulations to enforce anything. I think the law is there for purposes of distribution, which you cant do without permits anyway... so it leaves me to believe that you can brew any amount you want to. I speak for myself because I know there are some nuts on here lol, but I cant see myself ever coming close to the "legal limit" I just don't have the time, especially this being just a hobby of mine.