So I was thinking, you know how the domestic guys can go from iron to aluminum heads, and as a consequence run a higher compression (usually one full point I was told) on the same octane without less risk of detonation, due to the fact that aluminum transfers heat much better than iron.

Now, would the same principle work with an all aluminum rotary? Like I mean change the side and rear housings to aluminum? I know companies sell aluminum side housings (for like $1200 each I think), but would that reduce the chance of detonation in our iron-laden rotaries?

I imagine it would even if the rotor was still iron (they are iron aren't they?) because some parts of the side housing NEVER see a cool charge of air (like piston engines do) so they never get that cooling blast at all (like the rotor face DOES see some cool air once in a while), and the aluminum would help to relieve some of that heat from the side housing that doesn't see cool air.

Even better, get aluminum rotors (if they're iron...)

 

The rotor housings are already aluminum with an iron sleeve for seal contact. The side housings are cast iron. I believe racing beat sells aluminum side housings. But they are totally custom and expensive.
Your theory may not work well with the rotary since it is known to put out tremendous heat in comparison to a piston engine. I would be scared that the whole motor would warp if it got a little hot. Then you wouldn't have to worry about detonation killing your motor.
If I were to change anything to aluminum it would be the replacement of the stock radiator with a giant aluminum racing unit.

 

the engine would have less chance of blowing a coolant seal if it were all made of the same material (aluminum).

As it is, iron/aluminum/iron/aluminum/iron is a sucky way to do things, as they expand at different rates when they heat/cool