A. GOV can force convert the preferred to common before any action .... (yes you can then sue for 25 years)
B. preferred have a value in the case of a liquidation and there is enough money after debt only for the preferred
I own both as I do not know what may or may not happen and how it might turn out .... especially timing .... (e.g. common may win the highest factor of current price but that may take 4 years where preferred will get PAR in a year)