I guess that this would make it the same as for any other analog or digital hardware that you sell...
Meaning that if a 4bSST2 is "cosmetically" damage, you don't replace the case because this can only happen due to mishandling of the equipment. But if the problem is related to the quality of the outputed sound, and not due to abuse, then you replace/repair the faulty component.
If the same warranty, 20 years, is applied to the speaker realm, and transferable, wow!