Definitely not toe down. Ankling tends to reduce the activation of your hamstrings that are activated when you push your heel down a bit (we're talking clipless here). The hamstrings and the *** are the biggest muscles in the body, so you might as well use them! If you don't put your foot in the right position, you tend to use more quads, which cuts your power. In fact, if you do the "Lance" hill adjustment and move forward in your seat a tiny bit on a hill climb and pay attention to the foot position, you get even more power.