As an ENT physician and audiophile, I have to say ADEL at heart is a modified vent. I think if you were to graph the effect of the different modules on a graph, it will dampen certain frequencies to different degree. To understand vent in a traditional hearing aid read this article
http://www.hearingreview.com/2006/02/fitting-tips-how-do-vents-affect-hearing-aid-performance/. Look at Figure 2. When you create a vent hole or any dampening affect on the IEM side, it always drops the low frequency first. The larger the hole the more you dampen the low freq, the more compliant the diaphragm is as in the ADEL modules, the more you dampen the low freq. The physics and anatomy are such that you cannot electively dampen the high frequency first. The whole thing with more soundstaging and 3D imaging is just marketing. I wish sometimes manufacturers can be more transparent about this. If you ever get a custom sleeve made for IEM and ask them to leave a large vent hole on the custom sleeve, you can get different size plugs for the vent hole. By dampening the low-frequency, it will create the sense of more wide open sound stage. I have had 2 made by Westone for IE80 and XBA-Z5.
I still think what 1964 Ears is doing is an excellent idea. Other manufacturers should have done this a long time ago, but it's not some novel, revolutionary technology. It's a good adaptation of a long existing understanding of how the ear canal transfers sound. Whether it's worth the extra $ it's all up to the end users. The A12 is on my list as one of the next CIEM choices.