Themken: I would not mind finding a cheap 5800X3D myself. Had a look at prices earlier today and the cheap upgrade for me would be the 5600 (non-X) but the one I would love to have is the X3D of course, or an all new system heh. Pricey.
Dark_art_: I'm sure you're aware of it, but the 5500 is actually decent for the price, it's been around 80 something discounted Euros around here looking at various online shops (normal price around 100). If you're stuck on first gen Ryzen it makes a quite cheap upgrade, now that most mobo's have a Bios update to support newer stuff.
For me, the 5950x is way more interesting than the X3D version. The couple extra fps on some modern games are meaningful when compared to the extra threads/efficiency and ease of use (like running older Windows versions), but of course, that's just me and my use case.
Regarding the memory, I've yet to see a kit of brand memory not working on non-launch Ryzen motherboards (not saying that don't exist), as mentioned, you're probably fine and the worst case is that you have to tune the memory manually.
Idling at 30 degrees (ambient 21 degrees) gets up to 72ish on a stress test and gaming framerates are now really smooth. I think those temps are good for the chip.
Witcher 3 Complete edition now runs like a dream in DX12 mode.
Thanks for the help and advice everyone.