I've had this driver for a couple (few?) years. I do like it better than the Lowther DX series, and as you'd expect, it's arguably not as good as the top-of-the-line Lowther PM alnico drivers. It might be very evenly matched (overall) to the PM6A though, generally speaking.
The 8" drivers, whether AER or Lowther, have a certain visceral, life-like quality on certain instruments -- it can be astonishing on cello, saxophone, other acoustic material. However, the 8" gutsy, room-filling sound comes at the price of upper midrange and treble. So I'm actually listening to the humble little 4" Fostex FE103En more than the AER's. It does not have the "gutsy body" but it has a more pure, smoother, refined midrange and treble (as you'd expect from a 4").
So it's a question of tradeoffs. I still own both drivers but the 8" drivers need a bigger room (and for you to sit further back from them, or digital EQ if you want to sit closer and more on-axis).
Just one person's experience of course.