No frame breaks or signs of fatigue in my BDR yet! 15900 miles and counting. #259. Mine is on the road every day I can and I have hit my fair share of bone jarring bumps in the road. I have also taken a good 60 mph run at a S10 pickup and came away alive
. The frame did not bend or break.
I have seen some posts about the very early builds way before mine that had some issues that have since been rectified.
I plan on open tracking mine soon and I personally would be more concerned with receiving a direct blow to the door of any replica cobra than I would be about frame fatigue of something as stiff as the frame in the BDR.