Jim Roseberry
The advantage to Thunderbolt (if you're using Thunderbolt 3) is that we now have "PCIe via Thunderbolt" drivers.
You have to be running a Z170x motherboard (with USB-C connection) and Windows 10.
Performance will be similar to using a PCIe card. 
Jim, what does this mean for current audio interfaces using Thunderbolt? Would you just swap out the Thunderbolt cable for a Thunderbolt to USB Type-C cable and would work fine?