Opps.
I have no idea. I have never heard of anyone I know offering to pay off their loan for a reduced amount with exception to someone who files Chapter 7 Bankruptcy and redeems the property for the value which could be lower than the loan balance.
I would guess it would not be very effective. Servicers typically would reject the idea based on the theory "if you do it for one why not all"
Let us know if you have someone try it and what the result is.