With reference to this post and your previous post, I have to ask, how many Core i7 quad CPU laptops, Sandy Bridge or not, have you used?

Core i5 laptops will definitely have better energy savings and battery life compared to Core i7 quads. You can say that for Turbo 2.0 some cores of the quads will shut down automatically, but this is the same they said for Turbo 1.0 Core i7 quads, and battery life with the standard 6 cell batteries was terrible with those - unless you switched off wifi, music, video, and just read a PDF all day.