I put Win10 on my Surface Pro 3 last night - a painless upgrade. I thought to try to install the pcr-800 drivers here on this Surface and (as expected) are still not working. This is not my normal music computer, so it's a good place to prove the viability of them and then upgrade the music machine.
From the Roland news pages, it looks like there are plans to support 10 for devices that support 8.1, so I'm hoping that happens for this kb.
BitFlipper - My Tranzport still works under Win8.1 - just have to run the driver installer in compatibility mode for Windows 7 and it runs right off. Hope you get reunited!