How important is a nvme SSD?

If I do go with the NVME, what’s the best way to do it? Should I reinstall?

And I’m not convinced this is worth it - sure in theory it should be a lot better, but the reviews I’m seeing on this are very mixed. For instance during loading, nothing on my computer is anywhere close to 100% - the cpu, gpu, disk, and network do not appear to be limiting factors in load time. My disk is at 1%, cpu at 10%-15% (with no thread over 50%), and gpu at 20-35%.