I think most aspects of one versus the other have been covered.
However coming from someone who openly admits to using both (love the freedom in wave riding with a waist and when looping or boosting prefer the solid feel of a seat which doesn't rub on my broken stick out rib) I will add this:
Changing harnesses helps not have repetitive stress on section of your body wether it be hips back or ribs. Since I kite a lot, it helps avoid stress injuries. Just another take on it...