So yeah I have been cooking on my Lang for a couple of years now. It's a custom 6'x13' trailer with a 60 deluxe on one side and a 40 original and chargriller on the the other. At the time I had a smaller truck (Tacoma) so I wanted more space on my trailer to haul tables, coolers, wood, etc - hence the wide body trailer design. Ben and the gang at Land built me a great pit. I now own a larger truck w/canopy (Tundra) so all that extra on-board space isn't needed.
Although I've cooked on traditional offset cookers, I have a lot more experience with Lang's reverse offset design (1/4" steel, non insulated) and how it's worked for me. While I can't for sure say the one is better than the other, I will tell you my experience with my Lang. It's an awesome pit. It didn't have much of a learning curve and was affordable for me. At the time, there were a few teams he in the Pacific Northwest using Langs as opposed to other trailer pits so I was able to study them closely.
I love the flavor and color I get on the meat. Yes, you need to feed it...not much sleep with that pit. Not like my Stumps which got me so much sleep it was almost criminal. That's a different story though...
I use cheap charcoal to get the steel hot then wood (100% of the time) to cook the meat. Depending on the type and dryness of the wood I will get an average of 1 to 1 1/2 hours of burn time before adding fuel. By raising a lowering the tongue and fiddling with the stack damper you will achieve more even temps throughout the cooker. I can generally achieve a 10 degree difference front to back but of course the closer you get to the fire box, the hotter and boy, it's hot down there. Like a microwave.
I am no engineer but I will say this: Ben needs to rethink the fire box dimensions and stack diameter on the smaller pit line (40 and 60 models). Bigger fireboxes and slightly wider stack diameters, IMO, will produce better draft and air-intake/fire combustion. This is NOT a criticism, rather an opinion from my experience...others' may vary :)
BBQ Pitmasters RGC Season 4