05-Nov-2016 - Note: I've reached the conclusion that I will entertain no more underpowered devices as they are ultimately so limited their return on investment vastly underperforms overpowered devices. This means chromebooks are no longer acceptabe acceptable.
Things will change, but at this point (late October, 2016), it appears that the Skylake processors are horrible for power management on Linux. This is for the mobile processors for laptops. Desktop processors aren't an issue. So anyone seeking a laptop upgrade may want to wait.
In any case, the Lenovo X2x0 series can be improved with a USB-C, M.2 storage, and a bit of weight taken off the machine (come on folks, at 1.3kg a diet is in order, Macbook Air 11" is 1.1kg, and the Macbook 12" is 0.9kg). Kabylake is on the horizon, though it remains to be seen if the power management can get worked out there. Likely mid- to late-2017 for answers to that. I'm adding this to my June 2017 calendar. Hopefully the five year old Macbook Air can limp along another year. Should work out.
For a desktop, especially for Intel NUCs with Skylake, there are no problems with running CentOS and getting decent power management.
Other items desirable in a laptop (one that will last 5+ years). 16gb RAM, expandable to 32gb, 500gb SSD, expandable to 1tb.