I don't think the peaks are lasting long enough to lead to significant compression when listening to actual music in my system.
What a speaker can do with a sine wave for several seconds is not of great interest to me, if it doesn't correlate with my actual listening experience.
I don't expect anyone to agree with me. Especially those with dynamic speakers. I think you bring up some very good points on thermal compression, such as the lengths of the peaks. For sure some music will be more forgiving than others.
Have you considered though that driver non-linearities above Xmax are another form of compression (as the voice coil travels further outside the linear region of the magnetic field with large cone excursion). Again horns tend to have an advantage there too.
A demo at RMAF is a great idea - if they will allow you to play that loud. Sheffield Labs Drum track is a good stress test.