the screen doesnt take that much battery, its the polling of data that is taking energy, i know i stream tune-in radio for about 2 hours everyday (drive to and from work) and ussually if i have a stock battery i'll be down to 84% just to drive to work, by about 4-5pmpm it be almost dead just as i arrive at the house.
I know for a fact if you live in area where reception are bad, this battery will ultimately get me through the day, as if you have the stock battery it will be dead by noonish, polling data is a big deal that's why Juice defender works so well because, it bassiclly put your phone into airplane mode and therefore conserve battery.
o and I dont Dim my screen, or do anything that would hinder the purpose of a smart phone. been using this battery since it came out and it's worth it, I cant imagine having anything less. the size is not a factor at all, even my friend who is into ecstatic (dont know why, its a ****ing phone) he even admit that it's not that big, it might weight a bit more but to me that makes it more firm in my hand.