Amethyst versus Nagaoka MP-150/MP-200

@three_paws I own the same Sumiko Amethyst cartridge as yours on an Opera Consonance Wax Engine TT, acquired in July 2020,  connected to different SS / tube amps and speaker pairings. 
After listening to classical and jazz LPs released ca. 1965-1985, and newer Pop/Jazz/Electronic/Contemporary Classical recordings ca. 2010-present I must say that I’m quite impressed with Sumiko’s tonal clarity and depth of sound. I have auditioned Nagaoka cartridges before with positive experiences, but for me I’m leaning towards Sumiko for the broad timbral ranges that I personally aim for in specific chamber, symphonic and electronic music genres. 
If you do decide to sell the Amethyst you can probably garner $370-$400 USD, depending on its condition.

Hope this helps!

@three-paws There are definitely times when I hear warmth, especially when playing jazz trios, jazz ensemble, beat mix tracks, DJ or electronic lounge beats. This is again the intention of those tracks, hence I used the term: “pure.” On the contrary, I wouldn’t put a Stravinsky symphony or Dua Lipa in the same “warm” category simply because of the varying genre. I value hearing sound as it was recorded - “as if you’re there” - which many of us appreciate. 
In visualizing your system I think you built a robust system deserving of different cartridges. But if you really want to sell there are outlets that will buy quickly. Good luck and happy listening! 

@three_paws Probably the wrong adjective, which is my fault. I was struggling in finding the best word choice earlier. I also sensed that, like me, you have different systems going on. This thread is an isolated subject. 

@three_paws
I’m not sure if you listen to vintage jazz in stereo or mono, or alternate depending on your source format. Some studios back-in-the-day definitely produced records that only sound best in mono, meaning through monoblocks post-preamp. But I agree that different Sumikos produce different results for different recordings; I’ve heard 5 types of Sumiko but again, for me personally, my system sounds best with Amethyst (within the Sumiko line up that is). For your system and for what you listen to, yes, switching between Sumiko models could prove beneficial. Comparing Sumiko to Nagaoka, however, I would summarize as “pure” vs. “warm” if we had to use adjectives. Back to my system, the sound frequency, timbre, depth is performing to my musical format needs with the Amethyst. 

For some background as a child listening on my father’s systems, followed by further education and ongoing experimentation, it became clear that pairing is of utmost importance. You can have an amazing cartridge(s) but if the entire life cycle from power to speakers isn’t compatible then all is moot. Unfortunately we are at the mercy of the source, so the quality of each recording is another key point. This, however, we cannot control — for those who want total control this point is definitely out of our control.