Any benchmarks for non-pine64 pci to NVMe adapters?

[dukla2000]

1. Does using a higher quality pci to NVMe adapter improve the performance? Ideally, the PCI lanes should each be able to contribute 400 MB/s for a total of 1.6 GB/s. The only benchmarks i've seen cap out at 540 MB/s write and 1.3 GB/s read. The SSD being tested in those is rated to be able to achieve much higher performance in both areas. I don't know if the difference  is due to internal limitations of the processor or the PCI adapter itself. Hence my question.

I have 2 different PCIe/NVMe adapters. Neither noticably has any chip on them, not sure what else would materially affect quality. Both work fine, never felt either of them was faster or slower than anything else.
But for sure NVMe results (as per Bullet64 above) on iozone are hugely variable on ROCKPro64, in particular down to the kernel in use. 4.18 kernel results are significantly better than anything I have seen on 4.4 (as in 2 or 3 times better) which can make comparisons meaningless. Let alone the NVMe devices themselves.