@R-Typer
I have not yet upgraded to Windows 10 so I can not say for sure. Works fine on W7 x64. It uses very common USB drivers so I'm 99% it will work with the same drivers, but perhaps someone here can confirm.
The time it takes to write a floppy is a couple of minutes on the 1571 - it may depend on the model of drive you are using. It is slower than reading.
@Athanor
Thank you, replying to PM now.