Reddit mentions of High Point SSD7101A-1 NVMe RAID Controller

If you don't have a motherboard that supports the asus card, you can still buy the bare high point card for $400 and fill it yourself for less than a third the cost of the 4TB preconfigured high point.

It depends but it's negligible. There are some that basically act like just being a PCIe extender (so just wired like so on the PCB, basic) and this, there are some with controllers on board for true bifurcation or switch and/or handle both AHCI and NVMe on the same board (so possible one more step to read/write through even if transparent) and then there's the higher end with RAID controllers (that can still do JBOD, thus transparent) . It might have a very slight difference (like going through a PCH; regardless of lanes). But it would just show up if anything on benchmarks within the margin of error. No reason to be skeptical.

You want one of these. They have a PLX switch internally so you don't need bifurcation.

The cMP 5,1 uses SATA2 which will limit your io through put to 200-300mbs. USB 3 is fast enough. Honestly get yourself an ssd raid card and enjoy nvme speeds with a usb 3.1 pcie card. [nvme raid card](High Point SSD7101A-1 4X... https://www.amazon.com/dp/B073W71K4Z?ref=ppx_pop_mob_ap_share)

[sonnet usb 3](Sonnet Allegro Pro USB 3.1 Type A PCIe Card (Four SuperSpeed 10Gbps USB Connectors) https://www.amazon.com/dp/B07LG5TS6H/ref=cm_sw_r_cp_api_i_Bk6FDbW2P7GRP)

Also you can get thunderbolt 3 on this machine but it involves a reboot from boot camp.

[thunderbolt 3 card](Gigabyte GC-Titan Ridge (Titan... https://www.amazon.com/dp/B07GBZL93X?ref=ppx_pop_mob_ap_share)

how to get thunderbolt 3 working

No that wouldn’t work in most motherboards, you can buy the same thing in OP bare and make one yourself for cheaper tho https://www.amazon.com/High-Point-SSD7101A-1-Dedicated-Controller/dp/B073W71K4Z