One of the things I have noticed and think could be causing a kind of placebo effect is having the battery percentage meter on, the orignal battery icon is very small an only makes incremental changes throughout the day where the percentage meter obviously updates constantly thus creating an effect the batter is running down faster.

I have found that the percentage meter lowers and predicts usage based on how your using the phone so if for example you have been listening to music and browsing the net for news etc, it will often show a lower percentage because it's based on predicted usage, I have noticed my percentage increase if I have used the phone heavy for a little while then placed in my pocket for a little while also.

I remember a couple of years ago similar debates between nokia annd sonyericsson handsets and which were better for battery life one thing that became very apparent is that nokia would show high battery figures for longer and the rapidly drain towards the end of the day where sonyericsson were more progressive and slowly updated throughout the day. My point with this would be how many people are allowing their phones to drop into 10% for example as mines seems to drop initially a lot but hangs on a lot longer than expected when I get below 20%.