Home & Lock Screen bug
I noticed my 6 Plus was running warm during casual usage. This is the day after I set it up (iTunes restore) so any data conversion/reindexing should have completed. Battery usage stats were similar to the above, with Home and Lock Screen in around 15%. I rebooted the phone and it stopped running warm and after a day, Home and Lock Screen is around 3%. Getting much better battery life, similar to what's reported in reviews.
So it looks like there's a bug in iOS 8 and the iPhone 6 Plus in some situations. Possibly other devices though I did not notice this on the iPhone 5S.