While LTS has benefits, there are reasons to running the latest version you can get. Especially with new hardware, there are going to be updates to the relevant drivers which can improve the battery life a lot.
Over the first year after I bought the older X1, my battery life got an extra hour or so because of i915 module improvements. (I was following latest arch kernels)
Man, stick to 16.04, add PlayDEB and the official MESA releases.
If you want something recent based on GNU/Linux, desktop oriented, and fast, get SolusOS.