While we chose a roll-up door for our truck, we do not discount the advantages of swing doors. They are stronger. They seal the body better when closed. In reefer applications, they hold temps better. And in many cases, they provide additional door height. We considered all of those factors before choosing an overhead door. In our case, the roll-up door won out due to safety considerations, convenience, and the ability to protect our equipment if we are not at the dock but the truck is. As White Glove drivers, we carry a lot of valuable freight-handling equipment.
The point about the kind of freight your carrier offers is important when making the swing/overhead-door decision. We have driven trucks with both kinds of doors. Maybe once or twice in three years we had a load that could fit through swing doors that could not fit through barn doors. We're not general freight haulers. We seldom see loads that are taller than we are (under 6 feet).
Frankly, we don't want tall loads in our truck. If you load them with a pallet jack, they are top-heavy and dangerous for that reason. If a fork lift loads them, you have good reason to fear the forklift operator may damage your truck. If your truck is full of tall freight, your risk of a rollover is increased. Unless you are well-equipped with load bars, straps and such, and predisposed to use them, the risk that the freight may topple inside your truck is also increased, along with the risks of a freight damage claim.
Thus, overhead doors have and additional advantage. They keep tall freight out of your truck.
Yes, the arguement can be made that you'd rather haul tall freight than sit and haul no freight at all. We considered that but our experience was that tall freight is rare. When we sat, it was not tall freight that got us rolling again. We seldom saw tall freight, even when we had tall door openings.
Since we open the back door many times a week, the convenience and safety of a roll-up door outweighted the swing-door disadvantages. The slim chance that a tall load may one day get us moving when we might otherwise sit was more than offset by the roll-up door advantages.
One team's choice based on experience with a particular division with a particular carrier. What is best for us is not best for all.
When making the decision yourself, the best information you can consult is your own run journals. If you are not keeping track of the freight you haul, you should. With a good run journal, you won't have to ask others for advice about door types. Your freight will tell you.