I have a American professional ii stratocaster in roasted pine that is my favorite instrument of all time. I'm not a fender fanboy by any means, in fact I had always thought strats were kind of nerdy. After a few hours of playing it in the store I sold a Rickenbacker to buy the strat.
I got to play an American pro Ii jazz bass in roasted pine recently, and it had all the same features I love about my strat. If I had any extra gear or blood plasma to scrape together I would have bought it then and there.
I think the neck may have been a little thicker than usual. It was still jazz-bass skinny in width, but in depth I thought there was some extra meat there. I have big hands and generally prefer p-basses, but really loved this specific jazz neck.
Even if you have small hands, the extra thickness on the neck won't be an issue because the maple fretboards on the American professionals have very aggressively rolled edges. I've since manually rolled the edges of a few other fretboards I own, and while it's always a marked improvement nothing has ever felt as just right as an ampro ii maple fingerboard.
I subjectively think the roasted pine bodies are beautiful, and love that they are load and proud about being sustainable domestic lumber. Roasted pine bodies are also very lightweight. I don't believe in tonewood per se, but I can undeniably feel the roasted pine bodies vibrating more than those of most other instruments. I wonder if it's as simple as stiff + lightweight = resonant.
The finish is probably my favorite part of the guitar, and a reason all the previously mentioned components work so well. The "super-natural" finish on the back of the neck is awesome. It feels clean, dry, and fast. Whatever the body is finished in is very durable, my strat spends a lot of time getting played and riding in a truck and shows no evidence of that. The finish also probably contributes to the fact that the strat I own is the most stable instrument I've ever seen. I can for from warm Pacific coast to freezing Great Basin desert in a day, and the guitar won't even go out of tune.
As primarily a p-basses (and guitar) player, I'm not super familiar with jazz bass electronics. But in my uneducated fiddling with the knobs of that jazz I thought I heard treble bleed circuits. I know the am pro Ii strats have pretty fancy treble bleed circuits. The jazz pickups were also quiet, to the point I suspected they might be individually noise-cancelling.
