I run the latest release of Koreader and the KSM07. Never have a battery draining issue, but last Saturday I was feeling the need to take a closer look on this matter.
I make the changes on lua file on my H2O, adding the 15 delay on suspend time, read some for 15', my battery level was at 83% and then I leave my reader with its cover lid closed for about 4,5 hours.
When I was start to read again, the battery percentage was exactly the same. 83%...
I will try the same on my GloHD as well.