I like the fact that it's a positive connection.
Our '64 cord is hardwired in place. Every time we use it, it is pretty much bending the same way...after time, it will give out...we had ours replaced several years ago, but before that, we had to wiggle the cord sometimes to get things to work properly...we just thought that's how it was supposed to be. The main reason we had the cord replaced is, being that it is hardwired we have to store it in the bummer compartment. Our bumper compartment also has a loose/sliding door hatch that is for the stinky slinky to attach to the sewer system. A couple of years ago, on a long trip, the door jiggled open and the electrical cord started feeding out the hole. Thanks to a kind driver flagging us down, we figured out we had a problem and pulled over, but not before the end of the cord was lost...we were dragging it behind us about 10 feet.
That coupled with the comments others have made, convinced us to go with the Marinco on our '56. We will be switching over to a Marinco on our '64 when we change out the Univolt for a Charge Wizard next year.