James, interesting. Is this a special USB hub (or would "any typical" powered USB do)?
just for fun i just tested my gp+ with an old standard qtec 4-port usb 2.0 - hub (10euro's - 5 years ago),
output power-supply : 6v - 2100 mAmp,
my gp+ stills runs after ejecting the main power-cord (220V) of the gp+ ,
ther's a tiny problem: when i try to reboot the gp+, it is powered off just before restart..