I would say no. The monovalve either opens or closes. It doesn't care where the heat goes once it is open. I never had mine fail for the time that I owned it (around 70k miles? maybe more...can't remember).
I did however, have one fail on a 123 (300D). The rubber starts to tear, and hot fluid seeps past when it isn't supposed to.
btw...just in case.... You can just replace the insert, not the whole assembly.

Good luck!

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D