Roman helmets: Imperial Gallic/Italic and Ridge - comparisons and sources

[Condottiero Magno]

A Ridge helmet is significantly easier to build, this could easily justify its adoption, despite the different kind of structure is conceptually more subject to breakage, especially in a time of constant crisis that led to an increasing preference for the immediacy of the cavalry on the solidity of heavy infantry.

While a ridge helmet is easier to build, I'd like to see some evidence for it being "conceptually more subject to breakage."