"My fear is that the infringing parties will know that DM would prefer a one-time settlement and use that to understate future obligations (license fees). "

Of course they will understate future obligations.  That's their attorney's job.  Then they haggle.  I would guess that if DM is not satisfied with the end result they take it to the Eastern District of Texas.  That's OK by me....but any reasonable settlement will work wonders.