I will say that if the 243 is still with tritium indexes, I'd go o the 243 rather than the 24...
But if you let me choose between a 24 A/B or C, with the smooth bezel, and the tritium indexes, I'd rather go on the 24...
And even more, if you let me the choice between all the Subs, I'd go on a Pam 64, the 1st 1000 meters Sub!
To come back to your answer why a 243 over a 24 in the J series?
Not only because of the tritium on the 243 ( if ever there is still tritium on J series;, what I have some doubts...), but also because of the case, the glass, the overall look of the 243...
A real bad boy, not very esthetic, but quite pleasant to look at...
But, noce again, the King of the Bad Boy subs is the ...64!
Best.
Nicolas