USB is much better across the board, on Windows and Mac--and Linux is making both systems less important.
Let me explain:
When we began, Windows didn't support UAC2 at all, many Mac and Windows systems were plagued by draconian power management that effectively shut down USB ports when used with a DAC, and Linux streamers were still in the future. It was so bad that 80% of our inquiries were related to Windows/USB issues at one point.
Now, Windows 10 supports UAC2 natively, both Mac and Windows have gotten a lot better at power management, and Linux-based streamers are largely rendering both OSes obsolete in the audio world. Our inquiries related to USB have dropped to less than 10%, as more and more systems are simply plug and play.
Soon, with the official death of Windows 7 and the introduction of Unison USB™, there will be no real need for USB nervosa--our stuff will plug and play with all supported modern operating systems, and provide extremely high levels of performance. Or at least we think that's how it will go. As always, we'll see!