Like the simplicity. I'm not sure wear would be much more of an issue on the KA ring than other systems, so long as the welds are clean and polished.
At least with this setup it is easy to inspect & clean the part of line in question, rather than it being hidden in a ball or custom splitter.
A couple of points for anybody thinking about retofitting:
1) In the picture the flagging line is spliced whereas all the other are sleeved & stitched. Guess a sleeved line won't run through the gap smoothly. So you may need to change you line terminations.
2) Personal experience, using homebrew nylon blocks & also stopper balls with various different line types, has shown the hole diameter is critical. I.e. There is a very small range of hole size that will allow the line to slide through freely whilst also blocking the knot under high tension (this is definitely worth testing with at least all your body weight). As previously noted, it is easy to adjust (drill out) a plastic ball. This can't be done with the kite attitude ring.