I download plenty. I'll buy the music that I really like. I'll keep what I kinda like. I delete what I don't like. I'll buy what I kinda like when I can find something beyond a part time job.
Metal bands as a whole benefit greatly from downloading. It might hurt your Metallicas, Tools, Children of Bodoms, etc. but overall downloading absolutely helps the vast majority of metal acts. For every 1 person who would have bought something if downloading wasn't an option there's probably at least 3 who decided they liked a band after illegally downloading and end up buying it. For most bands discussed on these forums, the value of being discovered by your potential audience must absolutely trump losing some sales to leechers.