I have seen more than a few with cracked or broken stocks. 100 years of use will do that to even the best guns if a few falls, drop and too heavy loads are mixed in. A few popped ribs come to mind also. Two with top levers that were a problem, one an early pivot style, both were minor repairs.
Some of the guns have been shot until they are almost loose. Easy fix witha Lefever. One of my F grades had been shot so much that it had been completely rebuilt with bushed firing pins and a new dolls head surface. Must have been used a ton for the wear it had endured. It works well to this day by the way.
Lefever, as you point out, made an outstanding gun. His attempt to allow for wear by multiple adjustments was ahead of his time. But if he had better steels most of them would not be needed. I like his lines and the fact that he built 12s that go from just about 7 pounds to almost 9 pounds and they all feel alive in my hands. His stock work and engraving was far better than most of his day.
If someone wanted to bring back the Lefever in small gauges I would be forced to buy several. How about a 28 gauge Lefever with 28-30" barrels that tips the scales just over 5 1/2 pounds. That would be one very fast handling bird gun if there ever was one. Or even a 20 version that is 6 1/2 pounds.