See my correction above. Three models, including both 1000s and the ported 2000 have cloth grills. All others have metal grills.
EDIT: I have to correct myself again. The SB2000 Pro has a cloth grill as well. I have the prior SB2000 and it has a metal grill. I guess they "improved" it to...
Sorry Brian, but don't do that. It'll completely impede the driver's ability to do its job. Your suggestion of wrapping a cylinder sub would be an excellent solution. Something tough that can be replaced.