I believe the SE's use woofers from the old Contour line v/s the ones from the Audience line. That woofer is capable of more subtle sound and detail but will "bottom out" at very high power with a scary "Wackk" sound. As long as you don't drive it way too hard with a powerfull amp like Bryston no issues. This is based on my experience with a Contour 1.8 Mark II. Never had this issue with both my Audience speakers (50 and 52's).
The SE may also have an upgraded cross over for improved sound but in the standard 72 enclosure.
The SE may also have an upgraded cross over for improved sound but in the standard 72 enclosure.