OK - I'll kick it off! My answer is that they aren't mutually exclusive - because if you have a situation that is efficient, and that situation is not exposed to innovation, then it will atrophy rapidly and soon become inefficient.
The logical conclusion of that sentence is that innovation and efficiency are synergistic; and if they are synergistic that has to be the complete opposite of "mutually exclusive!"
But to dig deeper; innovation involves risk and efficiency is risk free. So to allow the synergy to be fruitful you do have to manage the risk!
So the logical question is "How do you manage the risk?" and "What is acceptable risk?"
Also, should we ask everybody to innovative (and less 'efficient' sometimes by trying something new etc) or should we ask some people to be innovative (an innovation team) and ask the others to do the same tasks over and over in predictable ways ~ which is most efficient and how big companies like to operate? I suppose I have kind of answered my own question but I'd love to have your and anybody else's thoughts on this.
Can, should we content designers and deliverers be innovative and effecient at the same time, as you suggest?