I find that shields and heal play fairly different in practice. For example, it's appealing to put a lot of heal on your dice, but it's just wasted whenever you're at max HP (which carries over between fights). With shields you start at zero each fight, so rolling a shield at the beginning is helpful. Finding a good balance between shields and health makes a significant difference (and that balance may differ over the course of the game).
I agree about being unable to tell which dice is which though - that would be super helpful.