Darvas describes a shadow that extends 5% beneath the box that he calls the danger zone. I don't recall the exact stop level for when price falls back into that shaded area but I see a problem. 5% isn't adaptive to the timeframe. It's based on an optimization he did on weekly charts. On a 5 min chart 5% is way too much when the entire day's price movement often is contained within 2% movement per day
Zeev on the other hand has defined a stop below the box that adapts to all time frames. The same reference works regardless of whether it's a weekly or a 5min chart. At least that's my understanding of it and Zeev might correct me if I'm wrong.
Regardless, I think it's important to develop these types of variants and welcome ideas along the lines of building a hybrid Darvas box. I don't expect the orignal algorithm to work, particularly because it's been published in a book and widely diseminated.