all traction kites need some line tension to fly I think it's inherent in the definition of a kite otherwise it would be a glider. The ability of a kite to recover and how it handles slack lines and apparent wind shift is another story.
The new Cloud Ds are the best at this right now IMO. It's not just that they weigh a lot less than the others It's their efficiency and slack line behavior in their ability fly well anywhere in the wind window without losing steering ability to pivot and drift due to bridle canopy shaping that allow them to recover even in extreme situations.
I have had Reos since V1 still have some V3 and V4s and 2 Hyperlink UL HL are great kites especially for boosting but HL even in the Ul version is limited by their shear canopy length and lack of canopy structure limits the slack line capability not to mention what happens if they fall in the surf. I'd still ride my inverted cloud over my Hyperlink flying normal any day in the surf. (BTW clouds fly fine inverted although an extremely rare situation to make happen. you have to try hard or be in unusually extreme shifty winds and still pretty easy to recover)
Agree all current designs have room to improve. Have high hopes for Ozone Alpha it seems a good attempt in the right direction have been asking Ozone for a kite like this for a few years and now 2 on order but at least from the initial images and data it still seems a couple gens behind the cloud D. We will see soon.