Yeah, my mb had an nvme m.2 slot, but it was pciex2, so the x4 card (most seem to be) didn't work. Why I went with an adapter.
The main thing lately is when I'm running a lot of containers/vms for workloads it tends to box down a little. Outside of that and 4k 3d, don't notice it ever. But the new stuff is only just starting to get better enough that I may upgrade next year sometime.
But in one thing you err: After a small custom BIOS mod, my home PC now boots from nvme - with a Z68 board (Sandy Bridge era), the module sitting in a PCIe adapter card. Was just a matter of adding some UEFI module.