Yes, I'm finding that as little as 1% roasted malts have a huge effect. I have an altbier that is about 11 SRM on tap that used around 1% carafa III and the roast character is quite apparent to me. The same was true with my last Vienna lager that used around 1% for coloring and was about 10 SRM. Never had it be so apparent before low oxygen. My black IPA, which is 7% midnight wheat, is super coffee/chocolate, more than usual; it's definitely overpowering the hops that are usually much more pronounced.