I saw that video... that is terrifying.
The ones I received look very similar to the ones that you used. The only difference is the delrin covers the sleeve as well. I am not sure who made them, but the guy I got them from is the AutoX chair for the chicago region and looking at his current and past builds he doesn't cheap out. I am sure he had them custom made from a reputable place. Him giving up on his STU 135 was the best thing that ever happened to me! He had a few pieces that either came off his car before he sold it, or never made it onto the car including these arms, HPA 1M strut brace, and a few other odds and ends.
I am going to mark them this week before heading to the full course at Autobahn CC on Friday. If the hold up to that I think they will survive autoX.
I might as well throw a picture of the front arms up as well.
sorry... I know this is your build thread.