All high excursion subs with a butyl rubber surround will have a problem with the surround deforming at the excursion limits. If you compare the ED sub on YouTube to the picture on the ED site, you will see that they changed from a tall, rubber surround to a flatter, wider, foam surround. It was a trade-off. The surround won't deform but they sacrifice cone area. Everything in subwoofer design is a tradeoff.
I run a pair of 15" TC-3000's in my home theater. They have a tall, rubber surround and more linear excursion than the ED driver being discussed. In this
YouTube video , you can see that this surround also deforms at the excursion limits. As you can see, it deforms equally all around. That's good. That means the surround is still keeping the cone centered. I've taken my sub to these limits as well. In a free-air test like I linked to, the sub has very little mechanical noise. I have no problems with a surround doing that as long as it is even and quiet about it. I'd much rather have additional cone area.
-Robert