I dunno, but there's something about those big-coil subs that makes them sound different, in a better way. The old 1200GTi for example, also equipped with a 4" coil, remains one of my favourite subwoofer drivers.
Yessir! That is why I picked up 4 of those babies on ebay
It's not just the coil, JBL really did their homework even back then, to symmetrize (is that even a word? lol) the magnetic field to make the fringe field above and below the gap almost identical.