You might check out Dell's Project Sputnik on the XPS. They are similar in weight to an Apple Air, made of aluminum and come with Linux installed and working with all the hardware.
Reinstalled it with Fedora and everything works without any configuration or tweaks needed.
With 4.12 kernel and TLP the battery life has been amazing (I can get about 24 hours at idle with screen on - about 2.55 Watts)
Also...powerful enough to drive dual 4K monitors if needed.