Why on Earth would you want to buy a laptop from a specialty Linux laptop vendor (at more expense for the same specs than a standard Windows OEM laptop) if you just need to optimize the installed Linux to get good battery life? Isn't that supposed to be the value-add of buying from a vendor that specializes in Linux laptops?
My suspicion is that a lot of people don't know how to configure a Linux OS for optimal laptop use. I imagine that even if one were to keep the Ubuntu installation that comes with the unit there are many further optimizations that can be performed to improve battery life.