I got close to 10,000 miles on mine, zero issues. Here's a good shot of the center bore and stud alignment:
Oh and stiffeners aren't happening. Too much to get them custom CNC'd.
I know 2 guys locally that are now running them, and I've seen maybe 4 or 5 across the net starting to run them.
click to go to photobucket for video: (open/open fail, but you get the idea)
This one just rolled out of the garage with 2 more cylinders and an exploder rear. It'll be getting different rubber soon...
This guy on NAXJA has them too.