First off, the nickel vs stainless debate is quite literally part of TalkBass legend. Here is one of numerous threads on the topic for anyone interested:
Nickel vs stainless and
Stainless Steel vs. Nickel Plated Steel – Sound Demo
I got my @Sado Sadowsky Blue Label Bright Nickel Rounds (SBN45B-Blue 45-65-85-105-130T) in my hands today. These are the same "line" (Blue Label) and gauge that came stock on my Sadowsky NYC PJ. First impressions: I cannot recall how old the stainless set on my bass were...I would guess at least 1 year, maybe older...but these Nickel strings are much brighter visually and the wrapping on the string is royal blue (compared to the navy blue wrap on the stainless strings). Maybe this is standard, but it looks awesome on my roasted maple headstock.
Before I swapped them, I played a little on the stainless so the feel and sound would be fresh in my mind. One of the reasons I wanted to try the nickels is that it seemed to me that the E string was a little thin (sonically) compared to the other strings and I hoped that the different ferrous properties of nickel would change that.
Installed, tuned up. As literally everyone before me as said, the nickel strings are slightly warmer and I would suggest the low end sounds fuller or maybe rounder is more accurate. I played through a few different warm up exercises.
SOUND: Warmer as I said, but they are easily as bright and crisp sounding as any new string I have played. The top end sounds different than the stainless; very clear and more bell or piano like to my ear. I tried some harmonics (Wooten's Amazing Grace). Though perhaps not as piercing as the stainless (I really need to clone my bass to do this properly), but certainly clear and again, bell-like. The "thinness" I mentioned in the E string was definitely reduced, especially on the 3rd and 5th fret.
FEEL: There is some debate as to whether nickel stings have more tension than stainless if you are interested in digging in; related to the higher mass of the winding forcing a tighter core tension to produce the right notes. The science makes sense to me, but I am not noticing this so far. I did not have to adjust my truss rod or string height and it feels the same as usual. The strings do feel smoother...which again has been endlessly debated in other threads and has been attributed to the nickel coating on the string which is smoother than the exposed stainless steel on a stainless set. All of that aside, they had the same "finger noise" that I attribute to new strings and that lessens with use.
Overall, I like these strings so far. I have a gig on Sunday and will put them to the test. Same venue I have played countless times over the last 3 plus years (no amp, bass to pitchblack tuner to radial bassbone to PA). I will update this "review" after the gig when I have 1) feedback from the band, 2) feedback from the engineer, and 3) a YouTube livestream to watch later.
If you are interested in more info on this topic, use the search. There are some very entertaining reads in there.