After 3 days of intensive head-scratching, and speaking with a certain person I now bring you the 100% sure way to dump/erase/write this Spansion N NOR flash (DIA-001)...
Firstly, connect your progskeet to the USB and run 'zadig.exe' - then select "Libusb0" as the driver to install for your progskeet device
THEN you need to use Winskeet4000-111004 to dump/erase/write (NOT the newest 111205)
SIMPLE!!! Credits to domelec for sharing the 'secret' - no really, a big thanks!
One thing to note - this isn't made clear anywhere... You can only use the WinUSB driver & Winskeet 111205 IF you have updated your Bitstream!!! Otherwise, use the older flasher & stick with the Libusb0 driver.