How to keep your Drupal 8 site synced with 8.x branch
All those comments are correct. While running Drupal 8 for a simple blog, brochureware or similar site is a good idea to test it, doing anything more is most definitely not. Upgrading any code on a production site without testing it first is a bad idea, upgrading it with code which is openly declared to be possibly broken is a spectacularly bad one.

So: build you site, upgrade locally occassionally, be ready to export your content (somehow) and reimport it into the new one (somehow). Neither of these are supported. Writing migrate sources for D8 and a CSV source and target pair would be appreciated and quite possibly would work well for this scenario. You can find me in #drupal-migrate on freenode IRC should you want to work on this.