So EZ was correct in his findings that the "wall" charger charges twice that of the usb? 1a - loss of 20% = 800mA and 500mA - loss of 20% = 400mA
No. Just stop saying wall, ac, and usb. They are meaningless terms. All that matter is the MA rating of the charger. A 1000ma charger can flow twice as much current as a 500ma charger. Time from empty to full will be faster with the 1000ma charger. Not necessarily twice as fast.