PCIe mounted storage?

Has anyone tested PCIe mounted storage over SSD’s for TouchDesigner? Would be interested to know your thoughts. Im planning to build a new system with a OS SSD and 2 SSD’s for storage but is PCIe now the way to go?

I haven’t personally tested, since I’m usually filling my PCIe slots or using tiny cases with no extra slots, but I have heard that they are supposed to be great. Would love to know if anyones been trying them.