My SKS chromoplastics lasted about 10 years of daily use before a crack appeared.
The modern metal hardware is a lot softer than they used to use so if you have older stuff, hang onto the metalwork.
They are as good as you need for touring or commuting.
Any tough unbreakable fender MUST be fitted with a safety quick-release at the front. Mine has activated once when some wire got jammed up. SKS come with a QR as standard.