mrz80
I guess it's in my blood
The 290s and 250/s have a totally different surround foam material from earlier XR and XRT models. They are not supposed to fail with time. They also have an advanced woofer mounting scheme to reduce enclosure resonances...
Alas, the one thing the surrounds on the LD/HP woofer *won't* survive is a mountain-climbing house cat who decides the new speakers would make a great vantage point. I've got small tears in the surrounds of both woofers on one side. Dumb cat.