So, Denis. What part of my post didn't get through, the part about 20 minutes in the developer or the part about how bad the stuff smells?
In truth, I seldom use caffenol because of the smell. It reminds me of one of my first summer jobs, as a short order cook on Cape Cod. The grease trap on the grill smelled like that after a heavy week of hamburgers. The effectiveness of the developer is not, IMHO, in question. It's worth however, after taking into account the smell, the long timing, the stained equipment and, oh ya, the smell, is a big question. I think I will continue to use it occasionally, but it's not my go-to developer, that's for sure. Sorry, John.