Ack, well, I was apparently confused this morning and got it backwards!

It is "obvious" that the calfs would expend more energy when dorsiflexed (heel down), it is NOT "obvious" at least to me that it would lead to an overall reduction in power.

I have absolutely no earthly idea why it would be a "big no-no" or that it could lead to injury. I naturally pedal with my heel down. It's down a lot at the top of my stroke and while it becomes more neutral towards the bottom it is still slightly down at the bottom. My bike fitter(s) know this (they always have to bring my heel to neutral to check my angles when fitting a bike to me), and haven't said a darn thing about it being "bad" (and we've even discussed it). Haven't hurt myself yet.

I DID hurt myself plantarflexed (toe down). My knees (which have never ached while riding bikes) hurt and hurt for a few days after as well. Hated the feeling as well.

Maybe I'll work on staying more neutral. My bet is I'll go back to my comfortable dorsiflex position, power loss or no.