Don't know if this helps but I also had a 2.75% 10 year mortgage against my primary residence. It represented less than 2% of the value of the house and I have no other mortgages on our other homes. There were 4 years left on the mortgage. It made no logical sense to pay it off.
HOWEVER, I cannot describe the satisfaction of having no mortgage to pay each month. I obtained far more enjoyment than I expected in having no mortgages to pay.
IF YOU PAY IT OFF, MAKE SURE THE BANK ACTUALLY DISCHARGES YOUR MORTGAGE OF RECORD AND GET A COPY OF THE RECORDED SATISFACTION OR DISCHARGE.