All Saleae Logic devices will work properly when connected to a USB 3.0 port, a USB 3.1 gen 1 port, or a USB 3.1 gen 2 port.
The Saleae USB 2.0 devices will operate at USB 2.0 speeds (called high speed), and the USB 3.0 devices will operate at USB 3.0 speeds (called super speed).
There is some confusion regarding the naming convention between USB 3.0 and USB 3.1.
Originally, USB 3.1 referred to a future USB standard to enable 10 gbps transfer speeds, over USB 3.0's 5 gbps. However, once released, the new 10 gbps standard was named USB 3.1 generation 2, whereas USB 3.1 generation 1 referred to the original USB 3.0 speed of 5 gbps.
There is no practical difference between USB 3.0 and USB 3.1 gen 1, although I'm uncertain if the specifications are completely identical. All USB versions are backward compatible. USB 3.0, USB 3.1 gen 1, and USB 3.1 gen 2 all support USB 3.0 and USB 2.0 devices.
There is no speed advantage using USB 3.1 gen 2 host controllers with the Saleae devices. The Saleae USB 3.0 devices can only operate at USB 3.0 speeds and would require a new hardware revision to support the faster transfer rates.