I charged my Oasis 2 to 100% last night. After finally getting it down to 1%. I figured that was good enough to test it. I didn't see the 4-5% drop I usually got after reading for a couple minutes, it did drop more gradually after that. I didn't read more than an hr. on it last night, so still testing. No big difference so far, but at least it hasn't dropped 4-5% from the start.
Also if Amazon plans to add immersion reading, if it's not just a rumor, then that might mean they will have to address the battery drain. I read somewhere that Kobo was able to increase battery life with one of their devices, with a software update ? Is this true ? Maybe it can be done with the Oasis 2 as well ?