As far as the size goes, I would determine that by the types of food you cook. If you are cooking a lot of ribs you are gonna need a bigger cooker than if you do pork butts. I have seen the Large Spicewine and I believe that cooker would do you right for just about any catering event.
As far as the Lang goes, I was speaking on a level of efficiency and productivity not passion. I would go insulated for the shear thought of not having to play with the smoker, in catering you have enough of a job to do without babysitting a fire. Notice the rusted out firebox, that comes from building bigarse fires just to get the temps up to a point where they will not require attention. Call them like I see them didn't mean to dish the Lang just meant to say there are more efficient offset smokers out there.
"Grilla in the Pits" "IMAGRILLA"
There's plenty of room for all of God's creatures.
Right next to the mashed potatoes.
Brinkmann Model 6668 Gasser
Stumps GF223 w/ Stoker assist
ECB that wins the $
Weber One-Touch Gold 22-1/2"
Large BGE w/ Stoker assist
55 gallon Drum Smoker
Wood Crate Cold smoker w/ smoke injector
No need for certification, I already know good BBQ!