Safety systems haven't received enough attention in the kiting industry, I agree. It almost seems like an after thought for some companies. Not bashing Best, but as one single example, that velcro attachment on the O-shit could have a warning to detach before use or something. They aren't the only ones, I am just using them as an example.
I also agree the current bow/hybrids can be more dangerous than C-kites with 5th lines when things go really bad.

I hate rigging a 5th line for a bunch of reasons, but would be interested in doing it for safety reasons, possibly.

How much more safety would a fifth line represent over a flag out system using one of the front lines? Some of the bows allow for attachment on one front line. I have modified my kites to use this approach. I am curious to hear some inputs.