My glo seems to have a bigger drain at the moment, but its only on its 2nd charge and is nothing like yours. I loose about 2 - 3 % a day in sleep. I did notice one strange thing though, on its factory charge the battery percentage hardly moved, but now I am taking it to work its draining in sleep a lot faster. No books have been added. Its as if when I am travelling its having a bigger drain, I was wondering if when its in its slip in my bag slight pressure is on the screen making it think that its been used. Or if even though the wifi is off, could it still be seeing networks and when I am moving its constantly looking out for various access points.
My old Kindle keyboard has been in standby for over 2 weeks and the battery meter has not moved. I think kobo should remove the % from future firmware releases.