I think it may get very lost in a dark beer. I steeped about 10 leaves in hot water for a few minutes and dumped it into a watermelon wheat for a week or so. No vegetal flavor (this is the second time I have done this) but the mint is very very subtle, even in a plain mint wheat, to the point that most people who tasted the beer noticed something interesting but couldn't identify what it was, when I told them it was mint they all recognized the flavor and liked that it was subtle, too much is overwhelming, like brushing your teeth.
I have tasted this beer and it is pretty minty though
not sure how oz's relate to the number of leaves I used, but I would bet he used a lot more