I play hard, but its not really something I consciously think about. I play as hard or as softly as the song requires. I might try playing harder or softer as the whim takes me. In general though, I play hard and I like a higher action so I can dig in. Geezer is definitely a big influence on me there.
Nailed it! Play to the song! If its a really driving/heavy part, then pound away! If its a more delicate/intricate part of the song... Play softer!