FWIW I was a big fan of Roy's speakers, and owned two pairs over the years. I did not own the Diamante, but I expect that they would be well worth renovating. I would also be inclined to first try replacing the foam, rather than tinkering with the drivers.
Green Mountain Audio
I picked up a set of Diamante's for cheap. They have trashed foam surrounds but otherwise seem fine. I plan on veneering the "marble" with a beautiful teak or rosewood- I haven't decided.The angles will look pretty cool with the right veneer. The marble is not so cool but rigid and heavy.
Curious if some upgraded drivers would improve the sound- as apposed to re-foaming. I realize this is a shot in the dark but my understanding is Roy from GMA has passed so not sure where to get driver advice. Open to any and all suggestions.