To bad that they stop develop C-Quad,i think this concept will resurface someday in the future design with water relaunchable feature.
Seriously doubt that. The kite had a lot of issues, that detracted from its few user friendly attributes. While it had great performance, it took quite a lot of fine control to get the best from it, otherwise it was actually a bit clunky to fly.
There was an early inflatable kite, the Seasmick(?) that was a very similar design but used inflatable tubes instead of solid fibreglass or carbon for the frame like C-Quads did.
Bridling on the C-Quad was prone to stretching, and this was another of the features that made it less popular. Same with the frame it was prone to breaking, as were the spine to LE connectors (major pain to repair/replace)
Videos were also made of the kite water relaunching, but this could only be achieved if the pilot was standing in shallow water (not shown in the videos). The floats just stopped them from sinking.
The optimal sizes were the smaller ones, they were pretty good in a buggy, quite fast and had good upwind, performance. Larger sizes had very high steering loads, and needed very large handles to fly them well. Amazing power for the size.
Backstraps, they are just a bad idea
No possibility of a safety release using one of them, only option was to let go of the whole thing, but because the power lines were under your arms you usually got a lofting or a good skull drag!
They were an interesting step to where we are today, no need to go backwards now!