Biggest difference I learned was the shelf and foot pocket of the WBBB.
I was sorely tempted to get a Hennessy with the addition of the side zipper (I still might). I read that several people didn't like the hook n' loop cause it caught debris in it. Also made it hard to reach down to get your boots off.
Ultimately though - The Hennessey Deep Jungle was 2 layers with a zipper and cost about $25 more that the WBBB. I still might get one...