There is a sonic trait on the CS2.4 that I wonder if you agree. Maybe Tom can provide his inputs.
In speaker design the baffle is pretty important to the sound which has to do with diffraction which I won't go into detail here since it will just create an even opposing opinions. Anyway, the CS2.4 has the coax fairly lower from the top of the speakers. For comparison, the CS3.7 has the coax almost at the top with the aluminum cone on top.
When in a recording where there is a hard right or left mix, in the CS2.4, I do feel that the sound comes from the baffle which spoils the 3-D illusions somewhat. In some of my designs, I place the tweeter right close to the top of the speaker so in such recording, the image flows more from the air as opposed from the baffle.
So in the CS2.4, the high freq. sound has to traverse the entire upper baffle so you hear the reflection from the baffle and not directly from the tweeter. I suspect that Thiel may have had this in mind, therefore on the CS3.7 design, the coax is placed at the top of the baffle to create a better 3D illusions.
An example of baffle design which improves diffraction is employed by Avalon Acoustic which has the tweeter close to the top with the baffle swept back. I think Thiel curved baffle such as the CS3.7 is even better but it will probably cost more to manufacture.
