The caps in these mics are not all that bad, usually it's the transformers and electronics, sometimes even the grill assembly that make a mic (such as the 2001) unuseable. Any mic can be modified. I've heard some mics with the C12VR cap (not a great mic by any means), which have been modified, that sound great.
The 'Royer Mod' appeared in a TapeOp Magazine, basically it tosses all the electronics and replaces the amp board with a new one with a tube and an external power supply. I have not heard the mod but it does look interesting.