I have both the SS door and high flow charcoal ring. I do like both, but if you have to choose the door wins,
Here is the stock ring inside of the CB high flow ring.
As you can see it is a tad bigger. Also, on the earlier 22 in WSM, the vents would bump into grate during adjustment ie the charcoal grate set a little too low. The CB ring has these tabs that elevate it enough to solve this problem. I think weber has since corrected this, but I do use it for long cooks as it is bigger than the stock ring.
Also, the CB ring has tabs that the charcoal grate rests on. You grab the CB ring and the grate comes with it. If you want more picks, I can go take a few that help explain a little better.