I have assisted on some smokes at Jerry's with his reverse flow and those things are great you never lose much heat when you open the door and it just seems to cook really evenly. I'm used to a gas set up that I have but I have a freind that wants me to help him with the design part. Thank god we have a lang close by.
You could go to www.pigroast.com or use the search feature at the top of the page and type in reverse flow, I quickly did that trying to find a link to give you but there are just too many to sort through, Basically there is a steel plate on the bottom of the cooking chamber that the heat and smoke travel under and then over the food back towards the firebox, eliminating hot spots. I have 4 smokers and for my taste this is the best one I own, easy to use, easy to clean and hard to make a mistake on it.
Great thread that link provides. I've also got a reverse flow smoker (Lang 48 Patio) and love it. Personally, I think it provides a convection style of cooking that provides an even-type distribution of heat.
Even heat, even smoke flavor. remember you can have a vertical reverse flow also. Not a lot of people out there realize this.
some people do say if you have a well insulated fire box and smoke chamber you do not need a "reverse flow" design for instants the jambo pits. they are not reverse flow but they are well insulated and have the smoke stack at grate level.