I’ve gigged both.
With all due respect to Sadowsky, that Marcus Miller V has by far and away the most Jazz Bass feeling neck I’ve yet played on a 5 string bass. The thing you have to watch out for is the standard Fender weight variability; because some of those MM V’s can be weighty. Mine weighed in around 8 pounds 10 oz. I am not a fan of bound and blocked necks; so that was one delta for me. Also, the preamp was....adequate at best. I basically sold mine because Roger was not offering his preamp as after market at the time; and the Fender preamp was finally not what I wanted. But, I do miss that bass. One of those decisions that doesn’t look so good in the rear view mirror.
But, I did use the sale to purchase a Sadowsky Metro 4 string; which was a fabulous instrument and led to a later Sadowsky NYC purchase. Which I still have, and which has one of the best Jazz Bass necks on it I’ve played in spite of the 12” fingerboard radius.
I’ve gigged both the Sadowsky nut widths on their 5 strings, the standard 1 7/8” and the Will Lee. The narrower WL feels a little better; but, in my case the distinction wasn’t a big deal. The thing I can’t get past on the Sadowsky 5 is the girth of the 19 mm neck. Just doesn’t feel Jazz Bass to me. At all. So, unfortunately, my 5 is a Fender Parts Bass with the Sadowsky preamp in it. Which is, despite the lack of pedigree, a pretty great instrument.
Meanwhile, Fender, in their infinite “corporate wisdom” has ditched that spectacular MM V neck taper. They clearly don’t understand when they have a good thing, confusing the design basis with the “signature” baloney/hype. That company mainly cares about selling a lot of guitars to parents of teenagers, and not so much about actual bass players. Their basses can be nice in spite of the reigning business model. Fortunately, Leo’s basic designs allow decent instruments, even when the company is doing their best to mess them up.