if you lower the brightness one notch, that might have more effect on the battery life than all the other parameters you mentioned.
Perhaps I'm exaggerating a bit, and is the biggest difference around 2 or 3 notches, but the 2010 and 2011 processors are all around 17W IRRC. That means that all the processors consume the same amount of battery-life at maximum performance.
If you do exactly the same tasks on all the laptops, the fastest processor should consume the least power as it takes a lower percentage of it's maximum capacity. In lab conditions you *might* be able to deduce that after intense testing, but in real life you'll be more busy testing than using the thing.
And after all the laptop is for using and not for testing (I assume this is the case with you as well.
What I noticed, coming from a 13" 2010 to an 11" 2011 is that the 11" has around 4-5 hours of use, if you push it it can have 5,5-6 hours. If I use the 13" i get around 6,5-7 hours and if I push it, I can get 9,5-10 hours.
That is a noticeable difference.
The difference between an i5, i7 and a C2D might be a minute or two if you are running 100% of the CPU all the time, and perhaps 5-10 minutes if you try to save energy as much as you can (e.g. 1 notch light, no back light, no wifi, bluetooth, just reading a book or writing one).
