Update to those who might take the Razer Core X (Chroma) route: I switched the 120 mm fan with a Noctua NF‑A12x25‑FLX and it was an easy drop-in. Ten minutes, one small X-shape screw driver. The noise level was very much OK even without it, but I changed it anyway, because ... I could ... and there was a YouTube video that showed it has an effect.
It did. Now the eGPU sound is just a whisper, with an under-the-desk mount. This particular Noctua model spins just like the old one, except that I can't hear it at all. The PSU sound is still there, but it doesn't penetrate the desk in any meaningful way. I'll leave the fan situation like it is now.
The Ethernet port on Chroma still doesn't work, no one should use that as a purchase criteria. I tried 3 different drivers, both with Big Sur and Catalina. The USB ports do work, and I guess that's nice. One less cable to connect all of the USB. I've got a USB hub behind the Razer.
Temps and wattage are low and stable. I now run TB ON and no Volta max CPU W limits, it's fine. Loud when heavily taxed, silent the rest of the time.
All 3 monitors get stellar performance, even with tons of open apps and lots going on. 27" 5k + 24" WQHD + 24" WQHD. Without the eGPU things could slow down a bit, with all 3 monitors busy. LG 5k TB3 is handled direct by the 5500M, and 2xWQHD Lenovo connected to the eGPU. So, two cables total. Opposite sides of the MBP.
I'm pretty sure I could throw a lot more at the eGPU, but no need at the moment. Using a "scaled resolution" of 4096 x 2304 --> 2048 x 1152 is not blurry on the 24" wing monitors, so no need to go 4k with them. No logical reason anyway.
I found that a native 2048 x 1152 is quite blurry, and pixel-to-pixel 2560x1440 makes things too small. A HiDPI Scaled Resolution is optimal with this combo. I used this script to make it work: https://github.com/xzhih/one-key-hidpi
I've set the "Prefer eGPU" checkbox ON for apps that might benefit from it, and many of them do. Microsoft Teams is one of those that doesn't, and I wish it did, because it's quite a hog. Maybe one day.
Didn't think about upgrading the fan...
ordered it. Great reviews.