what are the CONS/IMPLICATIONS of changing default parameter NLS_DATE_FORMAT from MMDDYY to MMDDYYYY.

What happens when couple of databases in local /remote network talk to each other with diffrent NLS_DATE_FORMAT.

I shouldn't change that parameter per our shop Database Administration Services policies and procedures. Seems developers have to change lots of their source, if format can't be changed. Couldn't convince 'em. Any help out there.