Part 2 of the problem: the "more durable" construction. Back in the 1970's these bars were made of much thicker material, thicker than the modern "more durable" bars in production today (which, in all fairness, are more durable than the aforementioned bear traps above).
However, this should not be construed as "better" in any way, shape, or form. Why? Source the Hurt Report which was a study from 1976-1981, specifically #39:
"Crash bars are not an effective injury countermeasure; the reduction of injury to the ankle-foot is balanced by increase of injury to the thigh-upper leg, knee, and lower leg."
So let's say your domestic bar is of similar construction, all it is doing is "relocating the injury" assuming the rider remains with the bike during the slide. Assuming "middle of the road construction", meaning somewhere between 70's grade durability and modern metric copper tubing, well...roll the dice and take your chances here for one or the other scenarios to play out.