It seems to me that Gomes didn't really have a solid claim though... he didn't actually claim that MERS did not have authority to foreclose-- he just suspected that they didn't, so he went to court to seek to require them to prove that they did.  That was part of his problem, according to my reading of the case.

Also, suppose that the wrong entity did foreclose.  Gomes is in default, so someone has the right to foreclose on him, and since there is no recourse on his purchase money mortgage, he can only lose the house and doesn't have to worry about a deficiency judgment, right?  So then if later the correct entity tries to foreclose and finds that the house is already sold, they can't get anything from Gomes-- he's already lost all he can lose, which is the house.  I'm sure that it would be a mess, but not for Gomes necessarily-- he's lost the same thing either way.  So how is he damaged, and why does he need to be able to have a way to make the foreclosing entity prove that they have the right to foreclose, unless he can show he is not in default and should not be foreclosed on, period, or he can prove that the foreclosing entity is not authorized?