Seems like you'd be dropping/ not having to make - 14 month of payments @ $1603 if you went with the new loan = $22,400 saved, if you went full term on paydown Since there is essentially no cost / points / appraisal / involved, its just your time and paperwork to make this happen.

If you pay it off early, versus 25 years, the "savings" will be significantly different than $22K . But that doessn't seem like a reason not to pay it off early if possible.

Well, probably you'll save more overall in interest payments than $22K if you can pay it off in 15 years. But they are 2 different equations... 26.2years vs 25 yrs cost comparison, and 15yrs vs 25 yrs.....sort of an apples to oranges comparison.