I've noticed quite a difference in performance by increasing octane from 91 to 93.25.
The min octane rating on the Gen2 cayman is 93 octane. Below that I think the ignition advance is dialed back to avoid detonation.
The most noticeable difference I see is the willingness to rev, starting at about 4000 RPM. With the higher octane it picks up revs faster - again I think due to more ignition advance.
Out here in California all we get is 91 octane peanut oil. I mix 25% 100 octane with 75% 91 octane to get 93.25.
I think the extra ignition advance will overshadow the lower BTU of the ethanol.
Lucky you if you can get 94 octane at the pump....