Hi and thanks for asking for me today.
In a strictly financial sense, the trade-off is a 4.25% rate for borrowing money (which can go up after you rfirst 5 years) versus what you can earn on your investments.
Keep in mind that interest paid is about $3400 a year currently, and may not be enough to make a difference in itemized deductions at tax time, so the interest is not offset by any (or much) tax savings.
With that in mind, can you get a "safe" return of 4.25% or better now? Probably not. CDs are lucky to be paying 0.5% Other investments may likely fare better, but right now it's a big question as to what risk you would need to undetake to get at least a 5% return (before taxes) to yield at least a 4.25% return.
On the other hand, if you feel you can use that inheritance to leverage an investment (for example, a rental property), then you may be better off investing as much as you can and using the income to help pay your mortgage.
In this case, I would say you have your choice based on your comfort of investing that $81K in something other than your mortgage, or getting rid of that montly obligation. My general advice is that a mortgage is fine as long as your income supports the monthly payments without being a burden. If you were to lose your job tomorrow, you still have enough cash to keep making payments as long as needed.
There are basically two good uses of debt: Use it to buy something that increases in value or to purchase and live in your home. Any other debt is dangerous and should be avoided.