<Large diaphragm mics like to break close to high spl's.>
????
Never heard of this. I just cannot see how it possibly could happen, considering the whole construction of the capsule.
The diaphragm displacement even under high SPLs is well below 1 micron. Even to consider that it was much more, still the backplate would work as a "stopper". Usually, the spacing between diaphragm and backplate is about 1 mil, or 24 micron. Think about it as a few times thinner than regular paper. Such a little excursion wouldn't be enough to break the diaphragm. There are other things like air cution between diphragm and backplate, which would effectively damp very high SPLs, etc. In fact, even ribbon mics, which considered much more fragile, can handle high SPLs easily. For example RCA BK5 could handle a gunshot sound right infront of the mic!
I would think the problem might possibly arise only using very old capsules with diaphragms made out of PVC. This material tends to dry over the time. If it breaks, it is a good sign that it's time to replace it.