Scott:

OK, here are some facts.

Those that have carbureted engines (O 320/360) and turn on carb heat see a much greater rise in inlet air temp since the air is heated by the exhaust pipe. 

That is not correct. They will see a much smaller IAT rise in temp than 100 degrees. Try it. I have. In my carbed engine, full carb heat will result in a 50dF rise--maybe. That's not close to 100 degrees and one should remember that the effects of IAT are not linear on detonation margin.
 
What is the large margin that has been reduced a little?  How is it related to Compression Ratio?  We need facts, not generalizations.

If you are interested in facts, then it should be measured, not guessed at. If those of you doing this have not taken an engine to a computerized test stand to accomplish this, then you are guessing. There are several factors in detonation margin. If we remove the fuel factors, we are left with IAT, compression ratio, and CHT as major players. Using higher CR AND higher IAT are both going the wrong way. There is a neat little graph of this in Taylor you can look up. It is pretty impressive how quickly the changes occur.

Walter