Thank you for a detailed response and making engineering and science from what to me was little more than a whim and maybe based on the odd report here and there.I never meant to suggest every person doing this is likely to destroy their driver if they open the back of the compression driver. I only meant to caution that it does significantly change the behavior of most drivers. If you are using 5-25W amplifiers on passive speakers, it's highly unlikely you could cause damage in even the worst case examples. It could create some significant changes in a passive crossover response, especially near and below the intended crossover. I recall both product examples more looking to the benefits of eliminating rear chamber confinement and resonances, with any rear driver output being a modest benefit. The intensity difference from the front vs rear will depend a lot on the horn type, angle, and size. The more loading and gain provided by the horn, the bigger the difference will be.
In the case of the impressive horns you showed pictures of, I would expect a greatly reduced output from the back side of the driver vs from the horn. Opening the back of the driver in your case likely reduced some chamber resonances and lowered the resonance of the driver. It appears the horn you have is much deeper and loads lower than the 2393, which is why the bulk of the impedance peak is much lower, but the rear of the driver removed likely shifts that peak lower as well as reducing chamber resonances. Both changes would be likely to contribute to the subtle benefits you described in an earlier post.
In the days when the Audio Asylum High Eff forum was brimming with knowledgeable folk, there was one of the highly regarded inmates who had a near-legendary bipole horn system using ElectroVoice drivers. This was never discussed and only mentioned in passing by others. Maybe Duke remembers who or what it was?