Hmm, I'm not convinced the weight forward designs are all that good. I prefer to have weight over the rear wheel. Check out the Surly Bikes Big Dummy .

But rather than a dedicated cargo bike, I'd much rather have an excellent road bike that can carry cargo -- something like the Surly Long Haul Trucker.

My 20-something year old mountain bike was built the old fashioned way, Cro-Moly steel with lots of braze ons. I've had a rack over the rear wheel and a small pack on the handlebars. Nothing that upsets the balance. It could easily take a set of panniers to carry more stuff. If I needed to carry more than that I'd start looking at trailers...