The original Geddy with the thin neck was not the best Jazz Fender made. Necks were a bit thin, and as mentioned above, could be prone to forward bow, where you couldn't loosen the truss rod enuff to get proper relief. Sound was OK, but the Brantley pickups, and others, greatly improved low end response.
The Mexican basses fixed the neck issue, but not the tonal issue. To me they sounded great as is. But had a very traditional Jazz sound. Slightly thin. And, playing the bass in modern gear, a bit of low end needs to be added to really get close to Geddy's sound. Nuttin wrong with that, either. He adds low end, too. But a lotta guys who just wanna run their amps flat would be disappointed.
The best Jazz Fender has made, and the best Geddy "clone" they made with the correct aesthetic was the 2010 to 2015, or so, American Deluxe Jazz. The black with Maple neck, blocks and binding, very much resembles Geddy's main. But, it has a better neck (asymmetrical, graphite reinforced, 5 bolt attachment to body with contour), better electronics (active/passive with a VTC, better pickups (third generation noiseless, tho there are two different versions, the earlier being the more aggressive) and a more legit overall sound. Its used price sits in the middle of the American and Mexican Geddy Signature. I own a 5 string version from 2010, and with steel strings run passive it simply nails Geddy's tone. Plus, no Geddy signature on the bass.
I wanted a Geddy, but I played a few different ones and went with the Deluxe. Just too many advantages.