I've got a new XPS13 edition. There's a few downsides like I absolutely have to run the latest kernel - 4.5.0-rc7 - to not have iGPU issues and not all WMI keys being supported properly (running Fedora rawhide). But other than that, I get about a 7w/s power consumption without optimising anything. That makes for 9-10hrs of usage, even under Linux!
Oh, and repairing them seems to be dead cheap as well. My XPS13 took a little dive, replacing pretty much the whole ultrabook put me back 320 EUR.
Nitpick: 7w/s is not the correct unit for power consumption. Watt is already energy per second, i.e. power consumption. Watt per second is the unit for change in power consumption.
Oh, and repairing them seems to be dead cheap as well. My XPS13 took a little dive, replacing pretty much the whole ultrabook put me back 320 EUR.