Yikes.
I replaced the surrounds on all four woofs around '95 or so with one of those DIY kits after the originals rotted. The replacements are holding up fine.
edit-
I'd love a pair of those Kappa 9'. A pair of those were the first speakers that I really made a huge sea-change impression on me. I was wiring up the switch box in a new display room when the first pair arrived, so I opened the boxes and set them up. I didn't get much soldering work done that afternoon. I kept turning around with my mouth open, just listening. My supervisor came in to see how things were going, and I said, " listen to these things" and we both sat there for about two hours.