The elongated upper horn bothers me more in terms of period correctness.
All the installment trouble you describe wouldn't be an issue for me since it is already installed...
The upper horn bothers me too, as it robs the outline of some of the gracefulness of the original.
The barrel jack is already installed, sure, but it will start to go wrong. It will slowly lose its grip, and you will lose signal continuity if the cable isn't at specific angles. I've had this in both the basses I've owned with these sodding things installed.
I'm not anti-progress, but this works:
The barrel jack gives you a slightly cleaner look as it doesn't need a plate, and can be recessed into the edge of your instrument. That is the only advantage I can think of.