e-postcard for Andy, I would assume that the connector that looks like the one on a battery stick will be the out put, t'other will plug into a battery. If the maker couldn't be bothered to mark them, I would have my fingers crossed behind my back.
The advantage of a switch mode chopper is that very little power is lost and thus practically no heat generated.
The disadvantage is the chopping of the supply to an inductive circuit, which can put large back EMF voltage spikes back into either or both of the supply and output power lines, causing local interference. Suppression as on a motor, and/or feeding the wires through ferrite rings or beads might help contain the interfering signal as well, but this is firmly into black art territory.
There is no way I could recommend using a linear resistor to drop more than half the supply voltage at any more than a few dozen milliamps in a closed environment like a boat. Apart from having to cart around the extra battery capacity which is going to be wasted, there is the need for heatsink(s) and fan(s), which between them will probably take up more space and payload than the extra battery.
One of those cases where you makes your choice and you pays your money.