Still technically counting as an upgrade because the case and SATA drives are the same, Memoria Mark II has sweeping upgrades to the CPU, RAM, graphics card, power supply, and case fans. The 12 threads and 32 GB RAM make her much better-suited towards workstation-type work--for my uses, primarily video rendering, while the RX 5700XT brings her quite a bit closer to hitting the golden 1440p 120 FPS mark in gaming--with FreeSync, now finally enabled after owning a compliant monitor for two years, helping smooth things out when things don't quite go that way.
The building process went amazingly smooth, with her posting on the first try. The only real issue was that I didn't quite understand how the RGB controller worked, and it took a bit of fiddling about before I finally got the front fans to light up.
One issue with the build itself is that the NH-D9L is unfortunately only just good enough to keep the 3600X cool, causing it to idle at 50 degrees and jump up to 80, or sometimes even 85 under load. This plays absolute hell with the CPU and case fans, even after applying a custom fan curve--while Memoria's dead silent at idle, as soon as temperatures go past 70 degrees, she becomes a jet engine for about 15 seconds before stabilizing to a rather normal speed. I plan to rectify the cooling issue soon by upgrading to the NH-D15--if that won't keep the temperatures down, I don't know what will (apart from an AIO, and I'm not quite ready for liquid cooling yet...)
Overall though, this upgrade went great, and I couldn't be happier.
EDIT: NH-D15 installed, and as expected, she's now whisper quiet.
EDIT 2: After an absolute gong show (see my review of the Strix 5700XT), I switched to an MSI Gaming X 5700XT.