I'm not sure how large the Attitude is, but acceptable size is definatly going to vary between people, and what you are doing. I am in high school, and we are not allowed to carry jackets. If we were, I would carry a lot more. But since we are not, the largest thing I carry is my key ring. It has a solitaire and a Tec 20 on it. It is fairly large, but small enough I find it acceptable. YMMV. If you are going to use the light a lot, I'd say an Arc, if not, maybe a photon. But the Arc isn't all that much more, maybe $10 than a photon, but is much MUCH cheaper to run.