I have 4 of the Apertures in my room at the moment, on loan from my dealer.
I have two behind the speakers and two on my front wall next to each other in between my speakers. All are approx 22inches off the ground.
They are very good and like others have mentioned do create better focus and are very good at making the singer clearer in the vocal delivery.
I find they do nothing in low bass. I have bass issues with my room and the Deqx in comparison provides significant help and easily discernible under 200hz to 400hz depending on the filter used. A 3db reduction under 200hz is even more noticeable when the recording has bass. The Apertures provide no help in this area. Having another 2 behind the speaker may be of benefit, however these things are not cheap.
In my room they are very good at providing better focus, clarity and transparency - they sort of sound right, quieter. IMO they are operating in the upper bass, MIDs and lower treble.
If you have bass gain issues, IMO these isnot the product to help, but obove those frequencies, I have heard positives and will continue to experiment with other placements.
Only my opinion thou.