Marv, thanks for providing HD distortion measurements for the Stratos. As for the spikes, IMHO it might not be the fact that the drivers are mounted loosely, but resulting from the drivers residing in a closed shell and thus the problem might be backwave related.
The spikes correlate to the dip in the FR around 4K. There is this dip between 3.5 and 4.5 KHz with both stock 35 and 75 drivers. The dip in the Stratos is just more pronounced, but it is still the same dip. My guess is that the spikes might be caused by reflections in the cup hitting the plastic driver back.
So, what I did was to cut out a ring of thin felt I used to dampen my Yamahas and cover the driver back with it, thus resting between driver back and foam damping. To my ears, running the Stratos through SineGen, the improvement is noticeable.
Seeing that you must have loads of time to try out mods, with absolutely no measurements taking your time at the moment, you would certainly not find the time to try this out on your Stratos? On the other hand, I am sure you might earn yourself half a Karma point by doing so!