[Kabigon]

I was more or less asking if premium would harm the engine due to the higher octane and higher combustion temp.

If anything, advanced ignition timing will lower exhaust gas temperatures.

 

[Kabigon]

I put 93 in my Titanium sometimes; I swear I gain a couple hp and an mpg or two, though I recognize it might be placebo.

It's not.

There was a long discussion about this.
Those that claimed that premium made no difference did so out of ignorance.

 

[Kabigon]

I personally think it is the gearing...

Of course that is part of the equation.

The other two MPG advantages that your SE had was significantly lower weight and higher compression (12:1 vs. 9.3:1).
Higher compression ratio = higher thermal efficiency.