Sometimes it pays to be patient with new technology. The latest XPS 17 9710 is the faster and more refined version of the last generation XPS 17 9700 with none of the battery draining irregularities.
https://www.notebookcheck.net/Dell-XPS-9710-quietly-fixes-the-charging-complications-on-last-year-s-XPS-17-9700.551479.0.html
The battery drain happens again in XPS 9710. Tested with power meter.