Legacy uses their large form factor, large midrange, methods in the Aeris. Imo, there would have to be some anomaly at work to draw such a conclusion, or if someone is a panel fan I can see them comparatively discussing the sweet spot as small in comparison.
I have heard Aeris several times at shows and it never had small sweet spot or poor off-axis sound. Roger Sanders' speakers are poor off-axis, and he lines up chairs like a runway in demos. Legacy places several chairs in a big square for listening. They are not afraid to have someone sit off-axis, and you can stand up around the Aeris and not have the sound collapse.
Now, Bill Dudleston prefers to cross the speakers before the listener, whereas I think that does unacceptable (to me) things to the soundstage and center image. I am not about to tell a man of his pedigree he's wrong, but I prefer a more traditional setup. If the reviewer was using the Legacy preferred placement, then that likely accounts for a lot of the description.
So, something as simple as positioning could be behind the different descriptions of such things.
As I have not used the Aeris in my home I will refrain from further comment. :)