Cool I have the same setup as you. Phanteks Evolv X case with the i9-9900K build last time too. Just upgraded to the Intel Z790 platform instead. But if you were to have bought your build during the Black Friday sale that just ended, then Ryzen platform would have been the way to go since it was cheaper than Intel's at that point.
Like you, I hate tearing down my builds. I would recommend only upgrading if you were using the RTX 4000 series of GPUs. That's when you'll feel the loss in performance. And even then, it depends on what the case may be. Like for me, I was using an M.2 PCIe Extender. It meant that my RTX 4090 was running at PCIe Gen 3 x8. Along with having that extender, it meant that I needed to mount my oversized Graphics Card to the front of the Phanteks Evolv X case or else, it will block my other PCIe slots. While it might fit, it was thermal throttling as the card had like 1cm of clearance from the glass. That's the only reason why I finally chose to upgrade to the current platform so as to reposition my card back horizontally and have accessible PCIe slots in case I needed them. But I bought a motherboard that supports all 4 of my M.2 SSDs while I did not use the 5th M.2 slot as it will cut my GPU's bandwidth in half again to PCIe gen 4 x8 which is still fine but. I'm going for maximum performance this time round.
Other than my rant, I did not have any issues on the Z390 platform. Everything was fast. But... I can tell you that there's some small little details that you'll notice when you upgrade. Like I use Stardock's Object Dock and on the i9-13900K, I noticed that it no longer hitches. It is just so smooth now. So there's some reason to upgrade. But it's really minor.
Like what others have suggested, I suggest looking for school holiday tertiary kids to help tear down and rebuild your PC. Even better if you can have them do it from your home.
