Just updated my "New" G1 from 1.10 to 1.11 with a Windows 8.1 laptop. Followed Casio's instructions precisely (Printed them out first - that helped a lot!) - had NO problems. Watching the bars leave and come back on both the keyboard LCD and the command prompt window was a helpful indication that something was going on.
Now all I need to do is download Talent 1.0.....