Since we seem to have reanimated this zombie, and the thread sort of turned into a Fender vs Sadowsky diatribe(

); perhaps, I will use this as an opportunity to update on my on going Jazz Bass investigations.
Marcus Miller somewhat famously was quoted as saying that a player needs to get their sound together, and then get on with playing. It has taken me a little longer than most (LOL); but, I think I'm finally getting there. And Roger's stuff is a big part of that.
A lot of this question is so relative to the individual player. A lot of cats can take a MIM Fender Jazz bass and be perfectly happy with it. For them, any kind of upgrade probably isn't "worth it."
To me, Roger's big contributions are his preamp for the Jazz Bass, his METICULOUS construction detail, and his setup perfection. You get those together in a Jazz Bass, and you get pretty close to what turns my gears. I can't speak to the P Bass aspects. To me, the P doesn't require a preamp; but Roger makes P's and then whether or not the player uses his preamp, the other two parts of a Sadowsky bass kick in; and a lot of cats on here love them.
Back to my own situation (and I'm a little slow, so please bear with me); I have been working with these two Jazz Basses the past few years:
View attachment 575540
That's a '97 Jazz Deluxe in Shoreline Gold and a Metro RV4. I am one who thinks the Fender on the headstock has some value in audition situations vs anything non-Fender; so, where I have been at is that the RV4 just sounds so amazing and plays so perfectly, I was trying to bring the Fender up to the same standards. You can see here I had already replaced the Fender preamp with the Sadowsky preamp.
The next thing that happened was that I put a bling pickguard on the Fender (what the heck, Shoreline Gold = bling, right?); and I became dissatisfied with certain elements of the Sadowsky humcancelling pickups, and replaced those with Delano JMVC4 single slugs. Actually, I tried to find a set of the Suhr single slug pickups, couldn't find them, and then opted for the Delano's because they had some similarities in construction. Then what happened was that the Delano's were SO superior to the Suhr's that I started using the RV4 exclusively. But, I didn't want to give up on the Fender. So, I had a fret level done on the Fender, which addressed the playability aspects; but, the sound still wasn't there. So, finally I bit the bullet and sprang for another set of Delanos:
View attachment 575535
And, voila, now these two basses pretty much behave and sound the same; and both meet my sound objectives.
Neglecting the pickups, I have about $1500 all told into the Fender; and that would compare to maybe $1700 to $1800 that you would pay for the RV4 on the used market (I purchased the Fender used). So, the difference is about $200 to $300; but, I had to do a lot of leg work and know what I was going for to get the Fender up to speed. Also, I installed the preamp myself and didn't count that.
My conclusion is that if you want to get the sound that Sadowsky Jazz basses offer; their market cost is "worth it." If you don't need that sound and an MIM is sufficient; then, they may not be "worth it."
That's my story and I'm sticking to it.
BTW, at this point, I am pondering moving the RV4 to have the NYC shop build me something a little more specialized. We'll see. Would that be "worth it?" It could be for me, for reasons I don't feel the need to justify. Good luck in your bass questing.