While the new JVC's are pretty awesome (I went with the rs2000/nx7 and a Paladin DCR lens for my 150" wide scope screen), I feel like their biggest strengths are in the built in tone mapping and the flexibility of the installation modes. The image sharpness and stability would be an improvement for you, but since you already have a Lumagen, I can't help but feel that the improvements would be too incremental. For me it was the combination of a lot of incremental improvements that made it all worth it. Plus I started with an Epson 5040 projector, so I had a lot of room to improve.
I definitely noticed an increase in fine detail over an e-shift projector, but the truth is I stop paying attention to that part once I get into the movie, so by going native 4k you will gain something, I'm not sure it is worth the price.
I don't recall if you use an a-lens or what your screen size is, but I have to say that I attribute a large amount of the improvement I got to the lens and the extra light it brought to my setup. Between the tone mapping and the a-lens, I gained so much brightness in HDR that I now use the color filter for ALL HDR content, no matter how dark the movie. The ~10% loss in these newer projectors is barely noticeable, so I didn't feel like I sacrificed any light for more color.
Don't get me wrong, I can't recommend the new JVC's enough, and I am simply thrilled every time I am in my theater now, and whenever I can do HDR, I get giddy about it. Next year (when the blow of the new projector, DCR lens, and finishing the rest of the basement subsides a little), I will either pick up a Lumagen or the MadVR Envy to get the dynamic tone mapping. But regardless of how happy I am with things now, I still have to suffer through bright corners that bother me more and more, and the contrast, while superior by far to my last projector, isn't better than the last couple generations of JVC. The nx9 lens would be awesome to have, just for a little more light, but I can't imagine improving on the sharpness and detail I have now, and I don't think the larger lens helps with the bright corners... These may not be issues for you, but I am just saying it to show that it isn't all roses and unicorns...
Anyway, just my 2 cents. In your shoes I would wait and go for the next iteration of laser projectors.