Marelon valves seem to be gaining in the market. They've been around long enough that any generic plastic problems like age hardening should have shown up by now.
The lack of galvanic problems offsets any questions of strength to my mind.
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I, myself, personally intend to continue being outspoken and opinionated, intolerant of all fanatics, fools and ignoramuses, deeply suspicious of all those who have "found the answer" and on my bad days, downright rude.