“Being Machmir on Pesach by definition is not Minhag Shtus, even if the Chumra is Shtus.”
True, but not eating g’brochs goes against the g’marah and seichel. At the very worst you have 18 minutes once your matzah is put into the hot soup. And if you want to be machmir with g’brochs, don’t do korech at the sedar because for sure there is water moisture on the lettuce. And don’t eat g’brochs on the last day of pesach because it may still be chometz. It’s a minhag shtus which I, unfortunately, adhere to; but I don’t go nuts…er, I mean, crazy over.