All our computers are on 8.1, including our i7-4930k ASUS P9X79-E WS system, which has a 4K TV and two Dell ST2340T FHD touchscreens attached, and running Cubase at 192k with 4ms round-trip latency.
I found that was not a huge step from W7, as when using multiple monitors, the desktop is the primary GUI for interaction. Many complained about the loss of the Start menu, though I found that many for whom it was an inconvenience were the minority still using it for program launching or who had built a lot of their workflow around it, when clearly W7 has shifted emphasis to the Taskbar (which is what the new GUI expands upon), and telemetry from millions of users showed that the majority had followed the hint and switched their primary launch focus from the menu to the taskbar.
It will all evolve, but I have found that the DAW side has not suffered from the upgrade to W8 then 8.1, especially since the need to control power usage resulted in reductions of numbers and spurious activities of OS utilities and drivers for all users.
Whatever of the two platforms Cubase runs on, we are being herded into distinct preferences by the platforms main drivers. With OSX, heavyweight users are being herded to hardware that is clearly biased to video and not audio, whereas, at least Windows is ‘blessed’ with a substantial and majority business user-base that keeps MS from making the same kind of blanket development decisions that may leave a minor user-base like DAWs out in the cold as well.