Primal is (to answer your question) way more important than low carb. You can eat 37 million kinds of low carb crap, but they won't feed you. You can eat nice startchy evnegtables and be well nourished, as long as your body can handle the starch. That said, low carb primal is fine. Nutrient deficient low carb is a mistake.
Grain Free since 2009, WP from 2005
~100% primal (because anything less makes me very sick)
Goal: hike across Sweden with my grandchildren when I retire in a few years