Things that act differently should look differently
Speaking of ripping off Don Norman, I'm reminded of this faucet I saw recently:
Instead of hot on the left and cold on the right, the knob on the left controls the temperature and the knob on the right controls the pressure. I noticed the temperature markings on the left knob, so I understood this. U. pointed out to me that this could be handy over time, just set the temperature to your favorite setting instead of having to balance the hot/cold mix every time. But this faucet looks like other faucets, and situations that could involve scolding hot water aren't times to play with conventions. Especially in this case, which was in a public restroom.
In my kitchen I have a faucet like this, which accomplishes the temperature setting feature while retaining the left and right convention and does so using only one control. But something about how the lever floats in two dimensions feels clumsy to me.