It really depends on a couple of different things. First being the dimensions of yours cooker. If you go with 2 doors, what is the distance between them. More is better. I think another thing to considers is ones ability when it comes to metal work. Two doors can mean twice the amount of work especially if they "spring" on you when you cut them.
Generally with one door you will need some sort of counter weight system. With one door you have a better chance of getting a whole hog in the cooker. One door in my opinion will cause you to have to have heavier material on grates due to
grates being bigger. Just to throw a few things at you!!!!!
CJ... I just went though the same question. I landed up going with the single because of the exact reason TuscaloosaQ said. I do see a day will I will want to toss something big in there. Think everything out now......