Not only does the secondary latch protect the hinge against over extension in high wind situations, but it provides an extra layer of protect against accidental canopy release in flight. When Zenith 601XL aircraft began experiencing a series of accidents starting in 2005, the FAA and other regulatory authorities around the world began to investigate. In 2009 the FAA issued a Special Airworthiness Information Bulletin that resulted in the modification plans which all Zenith 601XL owners were strongly encouraged to complete. During that period of investigation the Australian CAA felt that an unlatched canopy in flight might have resulted in one crash, causing them to mandate a secondary latch system in Austalian versions of the plane. While that was never proven to be the case, and while I am not registering my airplane in Australia, the idea of a seconday latch system makes sense for convenience and an extra measure of safety.
