Well, thanks FCC!
Basically the FCC confirmed for us that the G900 will be 2.4GHz wireless, and gave us a rough sketch of the silhouette of the bottom of the mouse. The mice appears to be roughly symmetrical from the bottom (though that says nothing of the actual design of the mouse), and using the size of the label given as a guideline, we can estimate that the bottom of the G900 is roughly 10cm long and 6cm wide. As a comparison, the G502 as a whole is 13.2cm long and 7.5cm wide (closer to 6cm wide at the grip when you deduct the width of the thumb rest); while the old G9x is 10.8cm long, and 5.8 / 7.3 / 8.2cm wide depending on the grip.
Of course, there may be protrusions and design elements that significantly change the size of the mouse (flip the G502 over and you'll see that the actual mouse is much longer than the bottom), but I'm cautiously optimistic that this mouse is closer to G9 size rather than G700 size.
EDIT: I just realized that the silhouette is the same shape and size as Logitech's M535... Could be just a deception .
Edited by roygbiv0415 - 1/20/16 at 9:00am