I have used them for almost a year with no serious issues. Although I did bend one when my friend drove my ERBE (BAD IDEA) and hit a soccer goal post at 3/4 throttle, along with breaking a pushrod. RPM arms didnt break tho. And other than that two of the dust boots tore.
I would strongly recommend them.
BUT, they can not be used if you are using LT rockers or your pushrods in the innermost hole.
Why is that? Im running both the LT rockers AND have my rods in the inner hole lol.