re-injecting a butt

I got inspired after reading the thread about re-injecting brisket during (and / or after the cook) to increase flavor and moisture and am thinking of trying it on one of my butts this weekend at a competition. I saw the concerns about making dark streaks in the brisket but was wondering if that would be an issue in the pork after it is pulled. I normally use a darker injection. Anyone tried this before? If so, what were the results?