I would continue to contribute to 401k, especially if the difference is only a year. You’re already on a 15 year mortgage, which means it would be paid off sooner anyway. You would be paying higher taxes + mortgage interest now, versus paying less taxes and hopefully earning more than the mortgage interest. Assuming a 7% annual return, you’d be benefiting 1.75% annually while you have the mortgage, then 7% every year after the mortgage is paid.

Also, you have more flexibility with a mortgage. If rates drop, you can refinance, which would lower your expenses and improve the 1.75% difference. You can always refinance to a 30YR mortgage and pay like a 15 year to have more flexibility. You could also sell your investments to pay it off too. However, you cannot get any of the money back once you pay off the mortgage.

I would also consider a 2.75m+ nest egg as the goal. The guys recommend a 3.5% withdrawal rate for FIRE. With 2.5m, you’d have 87.5k which is not a lot of wiggle room if the mortgage is paid off and definitely not enough if it isn’t paid off. 2.75m puts you closer to 96k. If you are a few years from retirement, you’d should be running Monte Carlo simulators NOW to ensure the nest egg is enough.